/*******************************************************************************
 *                                                                              *
 * Author    :  Angus Johnson                                                   *
 * Version   :  6.4.2                                                           *
 * Date      :  27 February 2017                                                *
 * Website   :  http://www.angusj.com                                           *
 * Copyright :  Angus Johnson 2010-2017                                         *
 *                                                                              *
 * License:                                                                     *
 * Use, modification & distribution is subject to Boost Software License Ver 1. *
 * http://www.boost.org/LICENSE_1_0.txt                                         *
 *                                                                              *
 * Attributions:                                                                *
 * The code in this library is an extension of Bala Vatti's clipping algorithm: *
 * "A generic solution to polygon clipping"                                     *
 * Communications of the ACM, Vol 35, Issue 7 (July 1992) pp 56-63.             *
 * http://portal.acm.org/citation.cfm?id=129906                                 *
 *                                                                              *
 * Computer graphics and geometric modeling: implementation and algorithms      *
 * By Max K. Agoston                                                            *
 * Springer; 1 edition (January 4, 2005)                                        *
 * http://books.google.com/books?q=vatti+clipping+agoston                       *
 *                                                                              *
 * See also:                                                                    *
 * "Polygon Offsetting by Computing Winding Numbers"                            *
 * Paper no. DETC2005-85513 pp. 565-575                                         *
 * ASME 2005 International Design Engineering Technical Conferences             *
 * and Computers and Information in Engineering Conference (IDETC/CIE2005)      *
 * September 24-28, 2005 , Long Beach, California, USA                          *
 * http://www.me.berkeley.edu/~mcmains/pubs/DAC05OffsetPolygon.pdf              *
 *                                                                              *
 *******************************************************************************/

/*******************************************************************************
 *                                                                              *
 * This is a translation of the Delphi Clipper library and the naming style     *
 * used has retained a Delphi flavour.                                          *
 *                                                                              *
 *******************************************************************************/
#include "pch.h"
#ifdef OCR
#include "clipper.hpp"

namespace ClipperLib
{

    static double const pi = 3.141592653589793238;
    static double const two_pi = pi * 2;
    static double const def_arc_tolerance = 0.25;

    enum Direction
    {
        dRightToLeft,
        dLeftToRight
    };

    static int const Unassigned = -1; // edge not currently 'owning' a solution
    static int const Skip = -2;       // edge that would otherwise close a path

#define HORIZONTAL (-1.0E+40)
#define TOLERANCE (1.0e-20)
#define NEAR_ZERO(val) (((val) > -TOLERANCE) && ((val) < TOLERANCE))

    struct TEdge
    {
        IntPoint Bot;
        IntPoint Curr; // current (updated for every new scanbeam)
        IntPoint Top;
        double Dx;
        PolyType PolyTyp;
        EdgeSide Side; // side only refers to current side of solution poly
        int WindDelta; // 1 or -1 depending on winding direction
        int WindCnt;
        int WindCnt2; // winding count of the opposite polytype
        int OutIdx;
        TEdge *Next;
        TEdge *Prev;
        TEdge *NextInLML;
        TEdge *NextInAEL;
        TEdge *PrevInAEL;
        TEdge *NextInSEL;
        TEdge *PrevInSEL;
    };

    struct IntersectNode
    {
        TEdge *Edge1;
        TEdge *Edge2;
        IntPoint Pt;
    };

    struct LocalMinimum
    {
        cInt Y;
        TEdge *LeftBound;
        TEdge *RightBound;
    };

    struct OutPt;

    // OutRec: contains a path in the clipping solution. Edges in the AEL will
    // carry a pointer to an OutRec when they are part of the clipping solution.
    struct OutRec
    {
        int Idx;
        bool IsHole;
        bool IsOpen;
        OutRec *FirstLeft; // see comments in clipper.pas
        PolyNode *PolyNd;
        OutPt *Pts;
        OutPt *BottomPt;
    };

    struct OutPt
    {
        int Idx;
        IntPoint Pt;
        OutPt *Next;
        OutPt *Prev;
    };

    struct Join
    {
        OutPt *OutPt1;
        OutPt *OutPt2;
        IntPoint OffPt;
    };

    struct LocMinSorter
    {
        inline bool operator()(const LocalMinimum &locMin1, const LocalMinimum &locMin2)
        {
            return locMin2.Y < locMin1.Y;
        }
    };

    //------------------------------------------------------------------------------
    //------------------------------------------------------------------------------

    inline cInt Round(double val)
    {
        if ((val < 0))
            return static_cast<cInt>(val - 0.5);
        else
            return static_cast<cInt>(val + 0.5);
    }
    //------------------------------------------------------------------------------

    inline cInt Abs(cInt val)
    {
        return val < 0 ? -val : val;
    }

    //------------------------------------------------------------------------------
    // PolyTree methods ...
    //------------------------------------------------------------------------------

    void PolyTree::Clear()
    {
        for (PolyNodes::size_type i = 0; i < AllNodes.size(); ++i)
            delete AllNodes[i];
        AllNodes.resize(0);
        Childs.resize(0);
    }
    //------------------------------------------------------------------------------

    PolyNode *PolyTree::GetFirst() const
    {
        if (!Childs.empty())
            return Childs[0];
        else
            return 0;
    }
    //------------------------------------------------------------------------------

    int PolyTree::Total() const
    {
        int result = (int)AllNodes.size();
        // with negative offsets, ignore the hidden outer polygon ...
        if (result > 0 && Childs[0] != AllNodes[0])
            result--;
        return result;
    }

    //------------------------------------------------------------------------------
    // PolyNode methods ...
    //------------------------------------------------------------------------------

    PolyNode::PolyNode() : Parent(0), Index(0), m_IsOpen(false)
    {
    }
    //------------------------------------------------------------------------------

    int PolyNode::ChildCount() const
    {
        return (int)Childs.size();
    }
    //------------------------------------------------------------------------------

    void PolyNode::AddChild(PolyNode &child)
    {
        unsigned cnt = (unsigned)Childs.size();
        Childs.push_back(&child);
        child.Parent = this;
        child.Index = cnt;
    }
    //------------------------------------------------------------------------------

    PolyNode *PolyNode::GetNext() const
    {
        if (!Childs.empty())
            return Childs[0];
        else
            return GetNextSiblingUp();
    }
    //------------------------------------------------------------------------------

    PolyNode *PolyNode::GetNextSiblingUp() const
    {
        if (!Parent) // protects against PolyTree.GetNextSiblingUp()
            return 0;
        else if (Index == Parent->Childs.size() - 1)
            return Parent->GetNextSiblingUp();
        else
            return Parent->Childs[Index + 1];
    }
    //------------------------------------------------------------------------------

    bool PolyNode::IsHole() const
    {
        bool result = true;
        PolyNode *node = Parent;
        while (node)
        {
            result = !result;
            node = node->Parent;
        }
        return result;
    }
    //------------------------------------------------------------------------------

    bool PolyNode::IsOpen() const
    {
        return m_IsOpen;
    }
    //------------------------------------------------------------------------------

#ifndef use_int32

    //------------------------------------------------------------------------------
    // Int128 class (enables safe math on signed 64bit integers)
    // eg Int128 val1((long64)9223372036854775807); //ie 2^63 -1
    //    Int128 val2((long64)9223372036854775807);
    //    Int128 val3 = val1 * val2;
    //    val3.AsString => "85070591730234615847396907784232501249" (8.5e+37)
    //------------------------------------------------------------------------------

    class Int128
    {
    public:
        ulong64 lo;
        long64 hi;

        Int128(long64 _lo = 0)
        {
            lo = (ulong64)_lo;
            if (_lo < 0)
                hi = -1;
            else
                hi = 0;
        }

        Int128(const Int128 &val) : lo(val.lo), hi(val.hi) {}

        Int128(const long64 &_hi, const ulong64 &_lo) : lo(_lo), hi(_hi) {}

        Int128 &operator=(const long64 &val)
        {
            lo = (ulong64)val;
            if (val < 0)
                hi = -1;
            else
                hi = 0;
            return *this;
        }

        bool operator==(const Int128 &val) const
        {
            return (hi == val.hi && lo == val.lo);
        }

        bool operator!=(const Int128 &val) const
        {
            return !(*this == val);
        }

        bool operator>(const Int128 &val) const
        {
            if (hi != val.hi)
                return hi > val.hi;
            else
                return lo > val.lo;
        }

        bool operator<(const Int128 &val) const
        {
            if (hi != val.hi)
                return hi < val.hi;
            else
                return lo < val.lo;
        }

        bool operator>=(const Int128 &val) const
        {
            return !(*this < val);
        }

        bool operator<=(const Int128 &val) const
        {
            return !(*this > val);
        }

        Int128 &operator+=(const Int128 &rhs)
        {
            hi += rhs.hi;
            lo += rhs.lo;
            if (lo < rhs.lo)
                hi++;
            return *this;
        }

        Int128 operator+(const Int128 &rhs) const
        {
            Int128 result(*this);
            result += rhs;
            return result;
        }

        Int128 &operator-=(const Int128 &rhs)
        {
            *this += -rhs;
            return *this;
        }

        Int128 operator-(const Int128 &rhs) const
        {
            Int128 result(*this);
            result -= rhs;
            return result;
        }

        Int128 operator-() const // unary negation
        {
            if (lo == 0)
                return Int128(-hi, 0);
            else
                return Int128(~hi, ~lo + 1);
        }

        operator double() const
        {
            const double shift64 = 18446744073709551616.0; // 2^64
            if (hi < 0)
            {
                if (lo == 0)
                    return (double)hi * shift64;
                else
                    return -(double)(~lo + ~hi * shift64);
            }
            else
                return (double)(lo + hi * shift64);
        }
    };
    //------------------------------------------------------------------------------

    Int128 Int128Mul(long64 lhs, long64 rhs)
    {
        bool negate = (lhs < 0) != (rhs < 0);

        if (lhs < 0)
            lhs = -lhs;
        ulong64 int1Hi = ulong64(lhs) >> 32;
        ulong64 int1Lo = ulong64(lhs & 0xFFFFFFFF);

        if (rhs < 0)
            rhs = -rhs;
        ulong64 int2Hi = ulong64(rhs) >> 32;
        ulong64 int2Lo = ulong64(rhs & 0xFFFFFFFF);

        // nb: see comments in clipper.pas
        ulong64 a = int1Hi * int2Hi;
        ulong64 b = int1Lo * int2Lo;
        ulong64 c = int1Hi * int2Lo + int1Lo * int2Hi;

        Int128 tmp;
        tmp.hi = long64(a + (c >> 32));
        tmp.lo = long64(c << 32);
        tmp.lo += long64(b);
        if (tmp.lo < b)
            tmp.hi++;
        if (negate)
            tmp = -tmp;
        return tmp;
    };
#endif

    //------------------------------------------------------------------------------
    // Miscellaneous global functions
    //------------------------------------------------------------------------------

    bool Orientation(const Path &poly)
    {
        return Area(poly) >= 0;
    }
    //------------------------------------------------------------------------------

    double Area(const Path &poly)
    {
        int size = (int)poly.size();
        if (size < 3)
            return 0;

        double a = 0;
        for (int i = 0, j = size - 1; i < size; ++i)
        {
            a += ((double)poly[j].X + poly[i].X) * ((double)poly[j].Y - poly[i].Y);
            j = i;
        }
        return -a * 0.5;
    }
    //------------------------------------------------------------------------------

    double Area(const OutPt *op)
    {
        const OutPt *startOp = op;
        if (!op)
            return 0;
        double a = 0;
        do
        {
            a += (double)(op->Prev->Pt.X + op->Pt.X) * (double)(op->Prev->Pt.Y - op->Pt.Y);
            op = op->Next;
        } while (op != startOp);
        return a * 0.5;
    }
    //------------------------------------------------------------------------------

    double Area(const OutRec &outRec)
    {
        return Area(outRec.Pts);
    }
    //------------------------------------------------------------------------------

    bool PointIsVertex(const IntPoint &Pt, OutPt *pp)
    {
        OutPt *pp2 = pp;
        do
        {
            if (pp2->Pt == Pt)
                return true;
            pp2 = pp2->Next;
        } while (pp2 != pp);
        return false;
    }
    //------------------------------------------------------------------------------

    // See "The Point in Polygon Problem for Arbitrary Polygons" by Hormann & Agathos
    // http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.88.5498&rep=rep1&type=pdf
    int PointInPolygon(const IntPoint &pt, const Path &path)
    {
        // returns 0 if false, +1 if true, -1 if pt ON polygon boundary
        int result = 0;
        size_t cnt = path.size();
        if (cnt < 3)
            return 0;
        IntPoint ip = path[0];
        for (size_t i = 1; i <= cnt; ++i)
        {
            IntPoint ipNext = (i == cnt ? path[0] : path[i]);
            if (ipNext.Y == pt.Y)
            {
                if ((ipNext.X == pt.X) || (ip.Y == pt.Y &&
                                           ((ipNext.X > pt.X) == (ip.X < pt.X))))
                    return -1;
            }
            if ((ip.Y < pt.Y) != (ipNext.Y < pt.Y))
            {
                if (ip.X >= pt.X)
                {
                    if (ipNext.X > pt.X)
                        result = 1 - result;
                    else
                    {
                        double d = (double)(ip.X - pt.X) * (ipNext.Y - pt.Y) -
                                   (double)(ipNext.X - pt.X) * (ip.Y - pt.Y);
                        if (!d)
                            return -1;
                        if ((d > 0) == (ipNext.Y > ip.Y))
                            result = 1 - result;
                    }
                }
                else
                {
                    if (ipNext.X > pt.X)
                    {
                        double d = (double)(ip.X - pt.X) * (ipNext.Y - pt.Y) -
                                   (double)(ipNext.X - pt.X) * (ip.Y - pt.Y);
                        if (!d)
                            return -1;
                        if ((d > 0) == (ipNext.Y > ip.Y))
                            result = 1 - result;
                    }
                }
            }
            ip = ipNext;
        }
        return result;
    }
    //------------------------------------------------------------------------------

    int PointInPolygon(const IntPoint &pt, OutPt *op)
    {
        // returns 0 if false, +1 if true, -1 if pt ON polygon boundary
        int result = 0;
        OutPt *startOp = op;
        for (;;)
        {
            if (op->Next->Pt.Y == pt.Y)
            {
                if ((op->Next->Pt.X == pt.X) || (op->Pt.Y == pt.Y &&
                                                 ((op->Next->Pt.X > pt.X) == (op->Pt.X < pt.X))))
                    return -1;
            }
            if ((op->Pt.Y < pt.Y) != (op->Next->Pt.Y < pt.Y))
            {
                if (op->Pt.X >= pt.X)
                {
                    if (op->Next->Pt.X > pt.X)
                        result = 1 - result;
                    else
                    {
                        double d = (double)(op->Pt.X - pt.X) * (op->Next->Pt.Y - pt.Y) -
                                   (double)(op->Next->Pt.X - pt.X) * (op->Pt.Y - pt.Y);
                        if (!d)
                            return -1;
                        if ((d > 0) == (op->Next->Pt.Y > op->Pt.Y))
                            result = 1 - result;
                    }
                }
                else
                {
                    if (op->Next->Pt.X > pt.X)
                    {
                        double d = (double)(op->Pt.X - pt.X) * (op->Next->Pt.Y - pt.Y) -
                                   (double)(op->Next->Pt.X - pt.X) * (op->Pt.Y - pt.Y);
                        if (!d)
                            return -1;
                        if ((d > 0) == (op->Next->Pt.Y > op->Pt.Y))
                            result = 1 - result;
                    }
                }
            }
            op = op->Next;
            if (startOp == op)
                break;
        }
        return result;
    }
    //------------------------------------------------------------------------------

    bool Poly2ContainsPoly1(OutPt *OutPt1, OutPt *OutPt2)
    {
        OutPt *op = OutPt1;
        do
        {
            // nb: PointInPolygon returns 0 if false, +1 if true, -1 if pt on polygon
            int res = PointInPolygon(op->Pt, OutPt2);
            if (res >= 0)
                return res > 0;
            op = op->Next;
        } while (op != OutPt1);
        return true;
    }
    //----------------------------------------------------------------------

    bool SlopesEqual(const TEdge &e1, const TEdge &e2, bool UseFullInt64Range)
    {
#ifndef use_int32
        if (UseFullInt64Range)
            return Int128Mul(e1.Top.Y - e1.Bot.Y, e2.Top.X - e2.Bot.X) ==
                   Int128Mul(e1.Top.X - e1.Bot.X, e2.Top.Y - e2.Bot.Y);
        else
#endif
            return (e1.Top.Y - e1.Bot.Y) * (e2.Top.X - e2.Bot.X) ==
                   (e1.Top.X - e1.Bot.X) * (e2.Top.Y - e2.Bot.Y);
    }
    //------------------------------------------------------------------------------

    bool SlopesEqual(const IntPoint pt1, const IntPoint pt2,
                     const IntPoint pt3, bool UseFullInt64Range)
    {
#ifndef use_int32
        if (UseFullInt64Range)
            return Int128Mul(pt1.Y - pt2.Y, pt2.X - pt3.X) == Int128Mul(pt1.X - pt2.X, pt2.Y - pt3.Y);
        else
#endif
            return (pt1.Y - pt2.Y) * (pt2.X - pt3.X) == (pt1.X - pt2.X) * (pt2.Y - pt3.Y);
    }
    //------------------------------------------------------------------------------

    bool SlopesEqual(const IntPoint pt1, const IntPoint pt2,
                     const IntPoint pt3, const IntPoint pt4, bool UseFullInt64Range)
    {
#ifndef use_int32
        if (UseFullInt64Range)
            return Int128Mul(pt1.Y - pt2.Y, pt3.X - pt4.X) == Int128Mul(pt1.X - pt2.X, pt3.Y - pt4.Y);
        else
#endif
            return (pt1.Y - pt2.Y) * (pt3.X - pt4.X) == (pt1.X - pt2.X) * (pt3.Y - pt4.Y);
    }
    //------------------------------------------------------------------------------

    inline bool IsHorizontal(TEdge &e)
    {
        return e.Dx == HORIZONTAL;
    }
    //------------------------------------------------------------------------------

    inline double GetDx(const IntPoint pt1, const IntPoint pt2)
    {
        return (pt1.Y == pt2.Y) ? HORIZONTAL : (double)(pt2.X - pt1.X) / (pt2.Y - pt1.Y);
    }
    //---------------------------------------------------------------------------

    inline void SetDx(TEdge &e)
    {
        cInt dy = (e.Top.Y - e.Bot.Y);
        if (dy == 0)
            e.Dx = HORIZONTAL;
        else
            e.Dx = (double)(e.Top.X - e.Bot.X) / dy;
    }
    //---------------------------------------------------------------------------

    inline void SwapSides(TEdge &Edge1, TEdge &Edge2)
    {
        EdgeSide Side = Edge1.Side;
        Edge1.Side = Edge2.Side;
        Edge2.Side = Side;
    }
    //------------------------------------------------------------------------------

    inline void SwapPolyIndexes(TEdge &Edge1, TEdge &Edge2)
    {
        int OutIdx = Edge1.OutIdx;
        Edge1.OutIdx = Edge2.OutIdx;
        Edge2.OutIdx = OutIdx;
    }
    //------------------------------------------------------------------------------

    inline cInt TopX(TEdge &edge, const cInt currentY)
    {
        return (currentY == edge.Top.Y) ? edge.Top.X : edge.Bot.X + Round(edge.Dx * (currentY - edge.Bot.Y));
    }
    //------------------------------------------------------------------------------

    void IntersectPoint(TEdge &Edge1, TEdge &Edge2, IntPoint &ip)
    {
#ifdef use_xyz
        ip.Z = 0;
#endif

        double b1, b2;
        if (Edge1.Dx == Edge2.Dx)
        {
            ip.Y = Edge1.Curr.Y;
            ip.X = TopX(Edge1, ip.Y);
            return;
        }
        else if (Edge1.Dx == 0)
        {
            ip.X = Edge1.Bot.X;
            if (IsHorizontal(Edge2))
                ip.Y = Edge2.Bot.Y;
            else
            {
                b2 = Edge2.Bot.Y - (Edge2.Bot.X / Edge2.Dx);
                ip.Y = Round(ip.X / Edge2.Dx + b2);
            }
        }
        else if (Edge2.Dx == 0)
        {
            ip.X = Edge2.Bot.X;
            if (IsHorizontal(Edge1))
                ip.Y = Edge1.Bot.Y;
            else
            {
                b1 = Edge1.Bot.Y - (Edge1.Bot.X / Edge1.Dx);
                ip.Y = Round(ip.X / Edge1.Dx + b1);
            }
        }
        else
        {
            b1 = Edge1.Bot.X - Edge1.Bot.Y * Edge1.Dx;
            b2 = Edge2.Bot.X - Edge2.Bot.Y * Edge2.Dx;
            double q = (b2 - b1) / (Edge1.Dx - Edge2.Dx);
            ip.Y = Round(q);
            if (std::fabs(Edge1.Dx) < std::fabs(Edge2.Dx))
                ip.X = Round(Edge1.Dx * q + b1);
            else
                ip.X = Round(Edge2.Dx * q + b2);
        }

        if (ip.Y < Edge1.Top.Y || ip.Y < Edge2.Top.Y)
        {
            if (Edge1.Top.Y > Edge2.Top.Y)
                ip.Y = Edge1.Top.Y;
            else
                ip.Y = Edge2.Top.Y;
            if (std::fabs(Edge1.Dx) < std::fabs(Edge2.Dx))
                ip.X = TopX(Edge1, ip.Y);
            else
                ip.X = TopX(Edge2, ip.Y);
        }
        // finally, don't allow 'ip' to be BELOW curr.Y (ie bottom of scanbeam) ...
        if (ip.Y > Edge1.Curr.Y)
        {
            ip.Y = Edge1.Curr.Y;
            // use the more vertical edge to derive X ...
            if (std::fabs(Edge1.Dx) > std::fabs(Edge2.Dx))
                ip.X = TopX(Edge2, ip.Y);
            else
                ip.X = TopX(Edge1, ip.Y);
        }
    }
    //------------------------------------------------------------------------------

    void ReversePolyPtLinks(OutPt *pp)
    {
        if (!pp)
            return;
        OutPt *pp1, *pp2;
        pp1 = pp;
        do
        {
            pp2 = pp1->Next;
            pp1->Next = pp1->Prev;
            pp1->Prev = pp2;
            pp1 = pp2;
        } while (pp1 != pp);
    }
    //------------------------------------------------------------------------------

    void DisposeOutPts(OutPt *&pp)
    {
        if (pp == 0)
            return;
        pp->Prev->Next = 0;
        while (pp)
        {
            OutPt *tmpPp = pp;
            pp = pp->Next;
            delete tmpPp;
        }
    }
    //------------------------------------------------------------------------------

    inline void InitEdge(TEdge *e, TEdge *eNext, TEdge *ePrev, const IntPoint &Pt)
    {
        std::memset(e, 0, sizeof(TEdge));
        e->Next = eNext;
        e->Prev = ePrev;
        e->Curr = Pt;
        e->OutIdx = Unassigned;
    }
    //------------------------------------------------------------------------------

    void InitEdge2(TEdge &e, PolyType Pt)
    {
        if (e.Curr.Y >= e.Next->Curr.Y)
        {
            e.Bot = e.Curr;
            e.Top = e.Next->Curr;
        }
        else
        {
            e.Top = e.Curr;
            e.Bot = e.Next->Curr;
        }
        SetDx(e);
        e.PolyTyp = Pt;
    }
    //------------------------------------------------------------------------------

    TEdge *RemoveEdge(TEdge *e)
    {
        // removes e from double_linked_list (but without removing from memory)
        e->Prev->Next = e->Next;
        e->Next->Prev = e->Prev;
        TEdge *result = e->Next;
        e->Prev = 0; // flag as removed (see ClipperBase.Clear)
        return result;
    }
    //------------------------------------------------------------------------------

    inline void ReverseHorizontal(TEdge &e)
    {
        // swap horizontal edges' Top and Bottom x's so they follow the natural
        // progression of the bounds - ie so their xbots will align with the
        // adjoining lower edge. [Helpful in the ProcessHorizontal() method.]
        std::swap(e.Top.X, e.Bot.X);
#ifdef use_xyz
        std::swap(e.Top.Z, e.Bot.Z);
#endif
    }
    //------------------------------------------------------------------------------

    void SwapPoints(IntPoint &pt1, IntPoint &pt2)
    {
        IntPoint tmp = pt1;
        pt1 = pt2;
        pt2 = tmp;
    }
    //------------------------------------------------------------------------------

    bool GetOverlapSegment(IntPoint pt1a, IntPoint pt1b, IntPoint pt2a,
                           IntPoint pt2b, IntPoint &pt1, IntPoint &pt2)
    {
        // precondition: segments are Collinear.
        if (Abs(pt1a.X - pt1b.X) > Abs(pt1a.Y - pt1b.Y))
        {
            if (pt1a.X > pt1b.X)
                SwapPoints(pt1a, pt1b);
            if (pt2a.X > pt2b.X)
                SwapPoints(pt2a, pt2b);
            if (pt1a.X > pt2a.X)
                pt1 = pt1a;
            else
                pt1 = pt2a;
            if (pt1b.X < pt2b.X)
                pt2 = pt1b;
            else
                pt2 = pt2b;
            return pt1.X < pt2.X;
        }
        else
        {
            if (pt1a.Y < pt1b.Y)
                SwapPoints(pt1a, pt1b);
            if (pt2a.Y < pt2b.Y)
                SwapPoints(pt2a, pt2b);
            if (pt1a.Y < pt2a.Y)
                pt1 = pt1a;
            else
                pt1 = pt2a;
            if (pt1b.Y > pt2b.Y)
                pt2 = pt1b;
            else
                pt2 = pt2b;
            return pt1.Y > pt2.Y;
        }
    }
    //------------------------------------------------------------------------------

    bool FirstIsBottomPt(const OutPt *btmPt1, const OutPt *btmPt2)
    {
        OutPt *p = btmPt1->Prev;
        while ((p->Pt == btmPt1->Pt) && (p != btmPt1))
            p = p->Prev;
        double dx1p = std::fabs(GetDx(btmPt1->Pt, p->Pt));
        p = btmPt1->Next;
        while ((p->Pt == btmPt1->Pt) && (p != btmPt1))
            p = p->Next;
        double dx1n = std::fabs(GetDx(btmPt1->Pt, p->Pt));

        p = btmPt2->Prev;
        while ((p->Pt == btmPt2->Pt) && (p != btmPt2))
            p = p->Prev;
        double dx2p = std::fabs(GetDx(btmPt2->Pt, p->Pt));
        p = btmPt2->Next;
        while ((p->Pt == btmPt2->Pt) && (p != btmPt2))
            p = p->Next;
        double dx2n = std::fabs(GetDx(btmPt2->Pt, p->Pt));

        if (std::max(dx1p, dx1n) == std::max(dx2p, dx2n) &&
            std::min(dx1p, dx1n) == std::min(dx2p, dx2n))
            return Area(btmPt1) > 0; // if otherwise identical use orientation
        else
            return (dx1p >= dx2p && dx1p >= dx2n) || (dx1n >= dx2p && dx1n >= dx2n);
    }
    //------------------------------------------------------------------------------

    OutPt *GetBottomPt(OutPt *pp)
    {
        OutPt *dups = 0;
        OutPt *p = pp->Next;
        while (p != pp)
        {
            if (p->Pt.Y > pp->Pt.Y)
            {
                pp = p;
                dups = 0;
            }
            else if (p->Pt.Y == pp->Pt.Y && p->Pt.X <= pp->Pt.X)
            {
                if (p->Pt.X < pp->Pt.X)
                {
                    dups = 0;
                    pp = p;
                }
                else
                {
                    if (p->Next != pp && p->Prev != pp)
                        dups = p;
                }
            }
            p = p->Next;
        }
        if (dups)
        {
            // there appears to be at least 2 vertices at BottomPt so ...
            while (dups != p)
            {
                if (!FirstIsBottomPt(p, dups))
                    pp = dups;
                dups = dups->Next;
                while (dups->Pt != pp->Pt)
                    dups = dups->Next;
            }
        }
        return pp;
    }
    //------------------------------------------------------------------------------

    bool Pt2IsBetweenPt1AndPt3(const IntPoint pt1,
                               const IntPoint pt2, const IntPoint pt3)
    {
        if ((pt1 == pt3) || (pt1 == pt2) || (pt3 == pt2))
            return false;
        else if (pt1.X != pt3.X)
            return (pt2.X > pt1.X) == (pt2.X < pt3.X);
        else
            return (pt2.Y > pt1.Y) == (pt2.Y < pt3.Y);
    }
    //------------------------------------------------------------------------------

    bool HorzSegmentsOverlap(cInt seg1a, cInt seg1b, cInt seg2a, cInt seg2b)
    {
        if (seg1a > seg1b)
            std::swap(seg1a, seg1b);
        if (seg2a > seg2b)
            std::swap(seg2a, seg2b);
        return (seg1a < seg2b) && (seg2a < seg1b);
    }

    //------------------------------------------------------------------------------
    // ClipperBase class methods ...
    //------------------------------------------------------------------------------

    ClipperBase::ClipperBase() // constructor
    {
        m_CurrentLM = m_MinimaList.begin(); // begin() == end() here
        m_UseFullRange = false;
    }
    //------------------------------------------------------------------------------

    ClipperBase::~ClipperBase() // destructor
    {
        Clear();
    }
    //------------------------------------------------------------------------------

    void RangeTest(const IntPoint &Pt, bool &useFullRange)
    {
        if (useFullRange)
        {
            if (Pt.X > hiRange || Pt.Y > hiRange || -Pt.X > hiRange || -Pt.Y > hiRange)
                return; // throw clipperException("Coordinate outside allowed range");
        }
        else if (Pt.X > loRange || Pt.Y > loRange || -Pt.X > loRange || -Pt.Y > loRange)
        {
            useFullRange = true;
            RangeTest(Pt, useFullRange);
        }
    }
    //------------------------------------------------------------------------------

    TEdge *FindNextLocMin(TEdge *E)
    {
        for (;;)
        {
            while (E->Bot != E->Prev->Bot || E->Curr == E->Top)
                E = E->Next;
            if (!IsHorizontal(*E) && !IsHorizontal(*E->Prev))
                break;
            while (IsHorizontal(*E->Prev))
                E = E->Prev;
            TEdge *E2 = E;
            while (IsHorizontal(*E))
                E = E->Next;
            if (E->Top.Y == E->Prev->Bot.Y)
                continue; // ie just an intermediate horz.
            if (E2->Prev->Bot.X < E->Bot.X)
                E = E2;
            break;
        }
        return E;
    }
    //------------------------------------------------------------------------------

    TEdge *ClipperBase::ProcessBound(TEdge *E, bool NextIsForward)
    {
        TEdge *Result = E;
        TEdge *Horz = 0;

        if (E->OutIdx == Skip)
        {
            // if edges still remain in the current bound beyond the skip edge then
            // create another LocMin and call ProcessBound once more
            if (NextIsForward)
            {
                while (E->Top.Y == E->Next->Bot.Y)
                    E = E->Next;
                // don't include top horizontals when parsing a bound a second time,
                // they will be contained in the opposite bound ...
                while (E != Result && IsHorizontal(*E))
                    E = E->Prev;
            }
            else
            {
                while (E->Top.Y == E->Prev->Bot.Y)
                    E = E->Prev;
                while (E != Result && IsHorizontal(*E))
                    E = E->Next;
            }

            if (E == Result)
            {
                if (NextIsForward)
                    Result = E->Next;
                else
                    Result = E->Prev;
            }
            else
            {
                // there are more edges in the bound beyond result starting with E
                if (NextIsForward)
                    E = Result->Next;
                else
                    E = Result->Prev;
                MinimaList::value_type locMin;
                locMin.Y = E->Bot.Y;
                locMin.LeftBound = 0;
                locMin.RightBound = E;
                E->WindDelta = 0;
                Result = ProcessBound(E, NextIsForward);
                m_MinimaList.push_back(locMin);
            }
            return Result;
        }

        TEdge *EStart;

        if (IsHorizontal(*E))
        {
            // We need to be careful with open paths because this may not be a
            // true local minima (ie E may be following a skip edge).
            // Also, consecutive horz. edges may start heading left before going right.
            if (NextIsForward)
                EStart = E->Prev;
            else
                EStart = E->Next;
            if (IsHorizontal(*EStart)) // ie an adjoining horizontal skip edge
            {
                if (EStart->Bot.X != E->Bot.X && EStart->Top.X != E->Bot.X)
                    ReverseHorizontal(*E);
            }
            else if (EStart->Bot.X != E->Bot.X)
                ReverseHorizontal(*E);
        }

        EStart = E;
        if (NextIsForward)
        {
            while (Result->Top.Y == Result->Next->Bot.Y && Result->Next->OutIdx != Skip)
                Result = Result->Next;
            if (IsHorizontal(*Result) && Result->Next->OutIdx != Skip)
            {
                // nb: at the top of a bound, horizontals are added to the bound
                // only when the preceding edge attaches to the horizontal's left vertex
                // unless a Skip edge is encountered when that becomes the top divide
                Horz = Result;
                while (IsHorizontal(*Horz->Prev))
                    Horz = Horz->Prev;
                if (Horz->Prev->Top.X > Result->Next->Top.X)
                    Result = Horz->Prev;
            }
            while (E != Result)
            {
                E->NextInLML = E->Next;
                if (IsHorizontal(*E) && E != EStart &&
                    E->Bot.X != E->Prev->Top.X)
                    ReverseHorizontal(*E);
                E = E->Next;
            }
            if (IsHorizontal(*E) && E != EStart && E->Bot.X != E->Prev->Top.X)
                ReverseHorizontal(*E);
            Result = Result->Next; // move to the edge just beyond current bound
        }
        else
        {
            while (Result->Top.Y == Result->Prev->Bot.Y && Result->Prev->OutIdx != Skip)
                Result = Result->Prev;
            if (IsHorizontal(*Result) && Result->Prev->OutIdx != Skip)
            {
                Horz = Result;
                while (IsHorizontal(*Horz->Next))
                    Horz = Horz->Next;
                if (Horz->Next->Top.X == Result->Prev->Top.X ||
                    Horz->Next->Top.X > Result->Prev->Top.X)
                    Result = Horz->Next;
            }

            while (E != Result)
            {
                E->NextInLML = E->Prev;
                if (IsHorizontal(*E) && E != EStart && E->Bot.X != E->Next->Top.X)
                    ReverseHorizontal(*E);
                E = E->Prev;
            }
            if (IsHorizontal(*E) && E != EStart && E->Bot.X != E->Next->Top.X)
                ReverseHorizontal(*E);
            Result = Result->Prev; // move to the edge just beyond current bound
        }

        return Result;
    }
    //------------------------------------------------------------------------------

    bool ClipperBase::AddPath(const Path &pg, PolyType PolyTyp, bool Closed)
    {
#ifdef use_lines
        if (!Closed && PolyTyp == ptClip)
            return false; // throw clipperException("AddPath: Open paths must be subject.");
#else
        if (!Closed)
            throw clipperException("AddPath: Open paths have been disabled.");
#endif

        int highI = (int)pg.size() - 1;
        if (Closed)
            while (highI > 0 && (pg[highI] == pg[0]))
                --highI;
        while (highI > 0 && (pg[highI] == pg[highI - 1]))
            --highI;
        if ((Closed && highI < 2) || (!Closed && highI < 1))
            return false;

        // create a new edge array ...
        TEdge *edges = new TEdge[highI + 1];

        bool IsFlat = true;
        // 1. Basic (first) edge initialization ...
        // try
        {
            edges[1].Curr = pg[1];
            RangeTest(pg[0], m_UseFullRange);
            RangeTest(pg[highI], m_UseFullRange);
            InitEdge(&edges[0], &edges[1], &edges[highI], pg[0]);
            InitEdge(&edges[highI], &edges[0], &edges[highI - 1], pg[highI]);
            for (int i = highI - 1; i >= 1; --i)
            {
                RangeTest(pg[i], m_UseFullRange);
                InitEdge(&edges[i], &edges[i + 1], &edges[i - 1], pg[i]);
            }
        }
        // catch(...)
        //{
        //     delete [] edges;
        //     return false;//throw; //range test fails
        // }
        TEdge *eStart = &edges[0];

        // 2. Remove duplicate vertices, and (when closed) collinear edges ...
        TEdge *E = eStart, *eLoopStop = eStart;
        for (;;)
        {
            // nb: allows matching start and end points when not Closed ...
            if (E->Curr == E->Next->Curr && (Closed || E->Next != eStart))
            {
                if (E == E->Next)
                    break;
                if (E == eStart)
                    eStart = E->Next;
                E = RemoveEdge(E);
                eLoopStop = E;
                continue;
            }
            if (E->Prev == E->Next)
                break; // only two vertices
            else if (Closed &&
                     SlopesEqual(E->Prev->Curr, E->Curr, E->Next->Curr, m_UseFullRange) &&
                     (!m_PreserveCollinear ||
                      !Pt2IsBetweenPt1AndPt3(E->Prev->Curr, E->Curr, E->Next->Curr)))
            {
                // Collinear edges are allowed for open paths but in closed paths
                // the default is to merge adjacent collinear edges into a single edge.
                // However, if the PreserveCollinear property is enabled, only overlapping
                // collinear edges (ie spikes) will be removed from closed paths.
                if (E == eStart)
                    eStart = E->Next;
                E = RemoveEdge(E);
                E = E->Prev;
                eLoopStop = E;
                continue;
            }
            E = E->Next;
            if ((E == eLoopStop) || (!Closed && E->Next == eStart))
                break;
        }

        if ((!Closed && (E == E->Next)) || (Closed && (E->Prev == E->Next)))
        {
            delete[] edges;
            return false;
        }

        if (!Closed)
        {
            m_HasOpenPaths = true;
            eStart->Prev->OutIdx = Skip;
        }

        // 3. Do second stage of edge initialization ...
        E = eStart;
        do
        {
            InitEdge2(*E, PolyTyp);
            E = E->Next;
            if (IsFlat && E->Curr.Y != eStart->Curr.Y)
                IsFlat = false;
        } while (E != eStart);

        // 4. Finally, add edge bounds to LocalMinima list ...

        // Totally flat paths must be handled differently when adding them
        // to LocalMinima list to avoid endless loops etc ...
        if (IsFlat)
        {
            if (Closed)
            {
                delete[] edges;
                return false;
            }
            E->Prev->OutIdx = Skip;
            MinimaList::value_type locMin;
            locMin.Y = E->Bot.Y;
            locMin.LeftBound = 0;
            locMin.RightBound = E;
            locMin.RightBound->Side = esRight;
            locMin.RightBound->WindDelta = 0;
            for (;;)
            {
                if (E->Bot.X != E->Prev->Top.X)
                    ReverseHorizontal(*E);
                if (E->Next->OutIdx == Skip)
                    break;
                E->NextInLML = E->Next;
                E = E->Next;
            }
            m_MinimaList.push_back(locMin);
            m_edges.push_back(edges);
            return true;
        }

        m_edges.push_back(edges);
        bool leftBoundIsForward;
        TEdge *EMin = 0;

        // workaround to avoid an endless loop in the while loop below when
        // open paths have matching start and end points ...
        if (E->Prev->Bot == E->Prev->Top)
            E = E->Next;

        for (;;)
        {
            E = FindNextLocMin(E);
            if (E == EMin)
                break;
            else if (!EMin)
                EMin = E;

            // E and E.Prev now share a local minima (left aligned if horizontal).
            // Compare their slopes to find which starts which bound ...
            MinimaList::value_type locMin;
            locMin.Y = E->Bot.Y;
            if (E->Dx < E->Prev->Dx)
            {
                locMin.LeftBound = E->Prev;
                locMin.RightBound = E;
                leftBoundIsForward = false; // Q.nextInLML = Q.prev
            }
            else
            {
                locMin.LeftBound = E;
                locMin.RightBound = E->Prev;
                leftBoundIsForward = true; // Q.nextInLML = Q.next
            }

            if (!Closed)
                locMin.LeftBound->WindDelta = 0;
            else if (locMin.LeftBound->Next == locMin.RightBound)
                locMin.LeftBound->WindDelta = -1;
            else
                locMin.LeftBound->WindDelta = 1;
            locMin.RightBound->WindDelta = -locMin.LeftBound->WindDelta;

            E = ProcessBound(locMin.LeftBound, leftBoundIsForward);
            if (E->OutIdx == Skip)
                E = ProcessBound(E, leftBoundIsForward);

            TEdge *E2 = ProcessBound(locMin.RightBound, !leftBoundIsForward);
            if (E2->OutIdx == Skip)
                E2 = ProcessBound(E2, !leftBoundIsForward);

            if (locMin.LeftBound->OutIdx == Skip)
                locMin.LeftBound = 0;
            else if (locMin.RightBound->OutIdx == Skip)
                locMin.RightBound = 0;
            m_MinimaList.push_back(locMin);
            if (!leftBoundIsForward)
                E = E2;
        }
        return true;
    }
    //------------------------------------------------------------------------------

    bool ClipperBase::AddPaths(const Paths &ppg, PolyType PolyTyp, bool Closed)
    {
        bool result = false;
        for (Paths::size_type i = 0; i < ppg.size(); ++i)
            if (AddPath(ppg[i], PolyTyp, Closed))
                result = true;
        return result;
    }
    //------------------------------------------------------------------------------

    void ClipperBase::Clear()
    {
        DisposeLocalMinimaList();
        for (EdgeList::size_type i = 0; i < m_edges.size(); ++i)
        {
            TEdge *edges = m_edges[i];
            delete[] edges;
        }
        m_edges.clear();
        m_UseFullRange = false;
        m_HasOpenPaths = false;
    }
    //------------------------------------------------------------------------------

    void ClipperBase::Reset()
    {
        m_CurrentLM = m_MinimaList.begin();
        if (m_CurrentLM == m_MinimaList.end())
            return; // ie nothing to process
        std::sort(m_MinimaList.begin(), m_MinimaList.end(), LocMinSorter());

        m_Scanbeam = ScanbeamList(); // clears/resets priority_queue
        // reset all edges ...
        for (MinimaList::iterator lm = m_MinimaList.begin(); lm != m_MinimaList.end(); ++lm)
        {
            InsertScanbeam(lm->Y);
            TEdge *e = lm->LeftBound;
            if (e)
            {
                e->Curr = e->Bot;
                e->Side = esLeft;
                e->OutIdx = Unassigned;
            }

            e = lm->RightBound;
            if (e)
            {
                e->Curr = e->Bot;
                e->Side = esRight;
                e->OutIdx = Unassigned;
            }
        }
        m_ActiveEdges = 0;
        m_CurrentLM = m_MinimaList.begin();
    }
    //------------------------------------------------------------------------------

    void ClipperBase::DisposeLocalMinimaList()
    {
        m_MinimaList.clear();
        m_CurrentLM = m_MinimaList.begin();
    }
    //------------------------------------------------------------------------------

    bool ClipperBase::PopLocalMinima(cInt Y, const LocalMinimum *&locMin)
    {
        if (m_CurrentLM == m_MinimaList.end() || (*m_CurrentLM).Y != Y)
            return false;
        locMin = &(*m_CurrentLM);
        ++m_CurrentLM;
        return true;
    }
    //------------------------------------------------------------------------------

    IntRect ClipperBase::GetBounds()
    {
        IntRect result;
        MinimaList::iterator lm = m_MinimaList.begin();
        if (lm == m_MinimaList.end())
        {
            result.left = result.top = result.right = result.bottom = 0;
            return result;
        }
        result.left = lm->LeftBound->Bot.X;
        result.top = lm->LeftBound->Bot.Y;
        result.right = lm->LeftBound->Bot.X;
        result.bottom = lm->LeftBound->Bot.Y;
        while (lm != m_MinimaList.end())
        {
            // todo - needs fixing for open paths
            result.bottom = std::max(result.bottom, lm->LeftBound->Bot.Y);
            TEdge *e = lm->LeftBound;
            for (;;)
            {
                TEdge *bottomE = e;
                while (e->NextInLML)
                {
                    if (e->Bot.X < result.left)
                        result.left = e->Bot.X;
                    if (e->Bot.X > result.right)
                        result.right = e->Bot.X;
                    e = e->NextInLML;
                }
                result.left = std::min(result.left, e->Bot.X);
                result.right = std::max(result.right, e->Bot.X);
                result.left = std::min(result.left, e->Top.X);
                result.right = std::max(result.right, e->Top.X);
                result.top = std::min(result.top, e->Top.Y);
                if (bottomE == lm->LeftBound)
                    e = lm->RightBound;
                else
                    break;
            }
            ++lm;
        }
        return result;
    }
    //------------------------------------------------------------------------------

    void ClipperBase::InsertScanbeam(const cInt Y)
    {
        m_Scanbeam.push(Y);
    }
    //------------------------------------------------------------------------------

    bool ClipperBase::PopScanbeam(cInt &Y)
    {
        if (m_Scanbeam.empty())
            return false;
        Y = m_Scanbeam.top();
        m_Scanbeam.pop();
        while (!m_Scanbeam.empty() && Y == m_Scanbeam.top())
        {
            m_Scanbeam.pop();
        } // Pop duplicates.
        return true;
    }
    //------------------------------------------------------------------------------

    void ClipperBase::DisposeAllOutRecs()
    {
        for (PolyOutList::size_type i = 0; i < m_PolyOuts.size(); ++i)
            DisposeOutRec(i);
        m_PolyOuts.clear();
    }
    //------------------------------------------------------------------------------

    void ClipperBase::DisposeOutRec(PolyOutList::size_type index)
    {
        OutRec *outRec = m_PolyOuts[index];
        if (outRec->Pts)
            DisposeOutPts(outRec->Pts);
        delete outRec;
        m_PolyOuts[index] = 0;
    }
    //------------------------------------------------------------------------------

    void ClipperBase::DeleteFromAEL(TEdge *e)
    {
        TEdge *AelPrev = e->PrevInAEL;
        TEdge *AelNext = e->NextInAEL;
        if (!AelPrev && !AelNext && (e != m_ActiveEdges))
            return; // already deleted
        if (AelPrev)
            AelPrev->NextInAEL = AelNext;
        else
            m_ActiveEdges = AelNext;
        if (AelNext)
            AelNext->PrevInAEL = AelPrev;
        e->NextInAEL = 0;
        e->PrevInAEL = 0;
    }
    //------------------------------------------------------------------------------

    OutRec *ClipperBase::CreateOutRec()
    {
        OutRec *result = new OutRec;
        result->IsHole = false;
        result->IsOpen = false;
        result->FirstLeft = 0;
        result->Pts = 0;
        result->BottomPt = 0;
        result->PolyNd = 0;
        m_PolyOuts.push_back(result);
        result->Idx = (int)m_PolyOuts.size() - 1;
        return result;
    }
    //------------------------------------------------------------------------------

    void ClipperBase::SwapPositionsInAEL(TEdge *Edge1, TEdge *Edge2)
    {
        // check that one or other edge hasn't already been removed from AEL ...
        if (Edge1->NextInAEL == Edge1->PrevInAEL ||
            Edge2->NextInAEL == Edge2->PrevInAEL)
            return;

        if (Edge1->NextInAEL == Edge2)
        {
            TEdge *Next = Edge2->NextInAEL;
            if (Next)
                Next->PrevInAEL = Edge1;
            TEdge *Prev = Edge1->PrevInAEL;
            if (Prev)
                Prev->NextInAEL = Edge2;
            Edge2->PrevInAEL = Prev;
            Edge2->NextInAEL = Edge1;
            Edge1->PrevInAEL = Edge2;
            Edge1->NextInAEL = Next;
        }
        else if (Edge2->NextInAEL == Edge1)
        {
            TEdge *Next = Edge1->NextInAEL;
            if (Next)
                Next->PrevInAEL = Edge2;
            TEdge *Prev = Edge2->PrevInAEL;
            if (Prev)
                Prev->NextInAEL = Edge1;
            Edge1->PrevInAEL = Prev;
            Edge1->NextInAEL = Edge2;
            Edge2->PrevInAEL = Edge1;
            Edge2->NextInAEL = Next;
        }
        else
        {
            TEdge *Next = Edge1->NextInAEL;
            TEdge *Prev = Edge1->PrevInAEL;
            Edge1->NextInAEL = Edge2->NextInAEL;
            if (Edge1->NextInAEL)
                Edge1->NextInAEL->PrevInAEL = Edge1;
            Edge1->PrevInAEL = Edge2->PrevInAEL;
            if (Edge1->PrevInAEL)
                Edge1->PrevInAEL->NextInAEL = Edge1;
            Edge2->NextInAEL = Next;
            if (Edge2->NextInAEL)
                Edge2->NextInAEL->PrevInAEL = Edge2;
            Edge2->PrevInAEL = Prev;
            if (Edge2->PrevInAEL)
                Edge2->PrevInAEL->NextInAEL = Edge2;
        }

        if (!Edge1->PrevInAEL)
            m_ActiveEdges = Edge1;
        else if (!Edge2->PrevInAEL)
            m_ActiveEdges = Edge2;
    }
    //------------------------------------------------------------------------------

    void ClipperBase::UpdateEdgeIntoAEL(TEdge *&e)
    {
        if (!e->NextInLML)
            return; // throw clipperException("UpdateEdgeIntoAEL: invalid call");

        e->NextInLML->OutIdx = e->OutIdx;
        TEdge *AelPrev = e->PrevInAEL;
        TEdge *AelNext = e->NextInAEL;
        if (AelPrev)
            AelPrev->NextInAEL = e->NextInLML;
        else
            m_ActiveEdges = e->NextInLML;
        if (AelNext)
            AelNext->PrevInAEL = e->NextInLML;
        e->NextInLML->Side = e->Side;
        e->NextInLML->WindDelta = e->WindDelta;
        e->NextInLML->WindCnt = e->WindCnt;
        e->NextInLML->WindCnt2 = e->WindCnt2;
        e = e->NextInLML;
        e->Curr = e->Bot;
        e->PrevInAEL = AelPrev;
        e->NextInAEL = AelNext;
        if (!IsHorizontal(*e))
            InsertScanbeam(e->Top.Y);
    }
    //------------------------------------------------------------------------------

    bool ClipperBase::LocalMinimaPending()
    {
        return (m_CurrentLM != m_MinimaList.end());
    }

    //------------------------------------------------------------------------------
    // TClipper methods ...
    //------------------------------------------------------------------------------

    Clipper::Clipper(int initOptions) : ClipperBase() // constructor
    {
        m_ExecuteLocked = false;
        m_UseFullRange = false;
        m_ReverseOutput = ((initOptions & ioReverseSolution) != 0);
        m_StrictSimple = ((initOptions & ioStrictlySimple) != 0);
        m_PreserveCollinear = ((initOptions & ioPreserveCollinear) != 0);
        m_HasOpenPaths = false;
#ifdef use_xyz
        m_ZFill = 0;
#endif
    }
    //------------------------------------------------------------------------------

#ifdef use_xyz
    void Clipper::ZFillFunction(ZFillCallback zFillFunc)
    {
        m_ZFill = zFillFunc;
    }
//------------------------------------------------------------------------------
#endif

    bool Clipper::Execute(ClipType clipType, Paths &solution, PolyFillType fillType)
    {
        return Execute(clipType, solution, fillType, fillType);
    }
    //------------------------------------------------------------------------------

    bool Clipper::Execute(ClipType clipType, PolyTree &polytree, PolyFillType fillType)
    {
        return Execute(clipType, polytree, fillType, fillType);
    }
    //------------------------------------------------------------------------------

    bool Clipper::Execute(ClipType clipType, Paths &solution,
                          PolyFillType subjFillType, PolyFillType clipFillType)
    {
        if (m_ExecuteLocked)
            return false;
        if (m_HasOpenPaths)
            return false; // throw clipperException("Error: PolyTree struct is needed for open path clipping.");
        m_ExecuteLocked = true;
        solution.resize(0);
        m_SubjFillType = subjFillType;
        m_ClipFillType = clipFillType;
        m_ClipType = clipType;
        m_UsingPolyTree = false;
        bool succeeded = ExecuteInternal();
        if (succeeded)
            BuildResult(solution);
        DisposeAllOutRecs();
        m_ExecuteLocked = false;
        return succeeded;
    }
    //------------------------------------------------------------------------------

    bool Clipper::Execute(ClipType clipType, PolyTree &polytree,
                          PolyFillType subjFillType, PolyFillType clipFillType)
    {
        if (m_ExecuteLocked)
            return false;
        m_ExecuteLocked = true;
        m_SubjFillType = subjFillType;
        m_ClipFillType = clipFillType;
        m_ClipType = clipType;
        m_UsingPolyTree = true;
        bool succeeded = ExecuteInternal();
        if (succeeded)
            BuildResult2(polytree);
        DisposeAllOutRecs();
        m_ExecuteLocked = false;
        return succeeded;
    }
    //------------------------------------------------------------------------------

    void Clipper::FixHoleLinkage(OutRec &outrec)
    {
        // skip OutRecs that (a) contain outermost polygons or
        //(b) already have the correct owner/child linkage ...
        if (!outrec.FirstLeft ||
            (outrec.IsHole != outrec.FirstLeft->IsHole &&
             outrec.FirstLeft->Pts))
            return;

        OutRec *orfl = outrec.FirstLeft;
        while (orfl && ((orfl->IsHole == outrec.IsHole) || !orfl->Pts))
            orfl = orfl->FirstLeft;
        outrec.FirstLeft = orfl;
    }
    //------------------------------------------------------------------------------

    bool Clipper::ExecuteInternal()
    {
        bool succeeded = true;
        // try
        {
            Reset();
            m_Maxima = MaximaList();
            m_SortedEdges = 0;

            succeeded = true;
            cInt botY, topY;
            if (!PopScanbeam(botY))
                return false;
            InsertLocalMinimaIntoAEL(botY);
            while (PopScanbeam(topY) || LocalMinimaPending())
            {
                ProcessHorizontals();
                ClearGhostJoins();
                if (!ProcessIntersections(topY))
                {
                    succeeded = false;
                    break;
                }
                ProcessEdgesAtTopOfScanbeam(topY);
                botY = topY;
                InsertLocalMinimaIntoAEL(botY);
            }
        }
        // catch(...)
        //{
        //     succeeded = false;
        // }

        if (succeeded)
        {
            // fix orientations ...
            for (PolyOutList::size_type i = 0; i < m_PolyOuts.size(); ++i)
            {
                OutRec *outRec = m_PolyOuts[i];
                if (!outRec->Pts || outRec->IsOpen)
                    continue;
                if ((outRec->IsHole ^ m_ReverseOutput) == (Area(*outRec) > 0))
                    ReversePolyPtLinks(outRec->Pts);
            }

            if (!m_Joins.empty())
                JoinCommonEdges();

            // unfortunately FixupOutPolygon() must be done after JoinCommonEdges()
            for (PolyOutList::size_type i = 0; i < m_PolyOuts.size(); ++i)
            {
                OutRec *outRec = m_PolyOuts[i];
                if (!outRec->Pts)
                    continue;
                if (outRec->IsOpen)
                    FixupOutPolyline(*outRec);
                else
                    FixupOutPolygon(*outRec);
            }

            if (m_StrictSimple)
                DoSimplePolygons();
        }

        ClearJoins();
        ClearGhostJoins();
        return succeeded;
    }
    //------------------------------------------------------------------------------

    void Clipper::SetWindingCount(TEdge &edge)
    {
        TEdge *e = edge.PrevInAEL;
        // find the edge of the same polytype that immediately preceeds 'edge' in AEL
        while (e && ((e->PolyTyp != edge.PolyTyp) || (e->WindDelta == 0)))
            e = e->PrevInAEL;
        if (!e)
        {
            if (edge.WindDelta == 0)
            {
                PolyFillType pft = (edge.PolyTyp == ptSubject ? m_SubjFillType : m_ClipFillType);
                edge.WindCnt = (pft == pftNegative ? -1 : 1);
            }
            else
                edge.WindCnt = edge.WindDelta;
            edge.WindCnt2 = 0;
            e = m_ActiveEdges; // ie get ready to calc WindCnt2
        }
        else if (edge.WindDelta == 0 && m_ClipType != ctUnion)
        {
            edge.WindCnt = 1;
            edge.WindCnt2 = e->WindCnt2;
            e = e->NextInAEL; // ie get ready to calc WindCnt2
        }
        else if (IsEvenOddFillType(edge))
        {
            // EvenOdd filling ...
            if (edge.WindDelta == 0)
            {
                // are we inside a subj polygon ...
                bool Inside = true;
                TEdge *e2 = e->PrevInAEL;
                while (e2)
                {
                    if (e2->PolyTyp == e->PolyTyp && e2->WindDelta != 0)
                        Inside = !Inside;
                    e2 = e2->PrevInAEL;
                }
                edge.WindCnt = (Inside ? 0 : 1);
            }
            else
            {
                edge.WindCnt = edge.WindDelta;
            }
            edge.WindCnt2 = e->WindCnt2;
            e = e->NextInAEL; // ie get ready to calc WindCnt2
        }
        else
        {
            // nonZero, Positive or Negative filling ...
            if (e->WindCnt * e->WindDelta < 0)
            {
                // prev edge is 'decreasing' WindCount (WC) toward zero
                // so we're outside the previous polygon ...
                if (Abs(e->WindCnt) > 1)
                {
                    // outside prev poly but still inside another.
                    // when reversing direction of prev poly use the same WC
                    if (e->WindDelta * edge.WindDelta < 0)
                        edge.WindCnt = e->WindCnt;
                    // otherwise continue to 'decrease' WC ...
                    else
                        edge.WindCnt = e->WindCnt + edge.WindDelta;
                }
                else
                    // now outside all polys of same polytype so set own WC ...
                    edge.WindCnt = (edge.WindDelta == 0 ? 1 : edge.WindDelta);
            }
            else
            {
                // prev edge is 'increasing' WindCount (WC) away from zero
                // so we're inside the previous polygon ...
                if (edge.WindDelta == 0)
                    edge.WindCnt = (e->WindCnt < 0 ? e->WindCnt - 1 : e->WindCnt + 1);
                // if wind direction is reversing prev then use same WC
                else if (e->WindDelta * edge.WindDelta < 0)
                    edge.WindCnt = e->WindCnt;
                // otherwise add to WC ...
                else
                    edge.WindCnt = e->WindCnt + edge.WindDelta;
            }
            edge.WindCnt2 = e->WindCnt2;
            e = e->NextInAEL; // ie get ready to calc WindCnt2
        }

        // update WindCnt2 ...
        if (IsEvenOddAltFillType(edge))
        {
            // EvenOdd filling ...
            while (e != &edge)
            {
                if (e->WindDelta != 0)
                    edge.WindCnt2 = (edge.WindCnt2 == 0 ? 1 : 0);
                e = e->NextInAEL;
            }
        }
        else
        {
            // nonZero, Positive or Negative filling ...
            while (e != &edge)
            {
                edge.WindCnt2 += e->WindDelta;
                e = e->NextInAEL;
            }
        }
    }
    //------------------------------------------------------------------------------

    bool Clipper::IsEvenOddFillType(const TEdge &edge) const
    {
        if (edge.PolyTyp == ptSubject)
            return m_SubjFillType == pftEvenOdd;
        else
            return m_ClipFillType == pftEvenOdd;
    }
    //------------------------------------------------------------------------------

    bool Clipper::IsEvenOddAltFillType(const TEdge &edge) const
    {
        if (edge.PolyTyp == ptSubject)
            return m_ClipFillType == pftEvenOdd;
        else
            return m_SubjFillType == pftEvenOdd;
    }
    //------------------------------------------------------------------------------

    bool Clipper::IsContributing(const TEdge &edge) const
    {
        PolyFillType pft, pft2;
        if (edge.PolyTyp == ptSubject)
        {
            pft = m_SubjFillType;
            pft2 = m_ClipFillType;
        }
        else
        {
            pft = m_ClipFillType;
            pft2 = m_SubjFillType;
        }

        switch (pft)
        {
        case pftEvenOdd:
            // return false if a subj line has been flagged as inside a subj polygon
            if (edge.WindDelta == 0 && edge.WindCnt != 1)
                return false;
            break;
        case pftNonZero:
            if (Abs(edge.WindCnt) != 1)
                return false;
            break;
        case pftPositive:
            if (edge.WindCnt != 1)
                return false;
            break;
        default: // pftNegative
            if (edge.WindCnt != -1)
                return false;
        }

        switch (m_ClipType)
        {
        case ctIntersection:
            switch (pft2)
            {
            case pftEvenOdd:
            case pftNonZero:
                return (edge.WindCnt2 != 0);
            case pftPositive:
                return (edge.WindCnt2 > 0);
            default:
                return (edge.WindCnt2 < 0);
            }
            break;
        case ctUnion:
            switch (pft2)
            {
            case pftEvenOdd:
            case pftNonZero:
                return (edge.WindCnt2 == 0);
            case pftPositive:
                return (edge.WindCnt2 <= 0);
            default:
                return (edge.WindCnt2 >= 0);
            }
            break;
        case ctDifference:
            if (edge.PolyTyp == ptSubject)
                switch (pft2)
                {
                case pftEvenOdd:
                case pftNonZero:
                    return (edge.WindCnt2 == 0);
                case pftPositive:
                    return (edge.WindCnt2 <= 0);
                default:
                    return (edge.WindCnt2 >= 0);
                }
            else
                switch (pft2)
                {
                case pftEvenOdd:
                case pftNonZero:
                    return (edge.WindCnt2 != 0);
                case pftPositive:
                    return (edge.WindCnt2 > 0);
                default:
                    return (edge.WindCnt2 < 0);
                }
            break;
        case ctXor:
            if (edge.WindDelta == 0) // XOr always contributing unless open
                switch (pft2)
                {
                case pftEvenOdd:
                case pftNonZero:
                    return (edge.WindCnt2 == 0);
                case pftPositive:
                    return (edge.WindCnt2 <= 0);
                default:
                    return (edge.WindCnt2 >= 0);
                }
            else
                return true;
            break;
        default:
            return true;
        }
    }
    //------------------------------------------------------------------------------

    OutPt *Clipper::AddLocalMinPoly(TEdge *e1, TEdge *e2, const IntPoint &Pt)
    {
        OutPt *result;
        TEdge *e, *prevE;
        if (IsHorizontal(*e2) || (e1->Dx > e2->Dx))
        {
            result = AddOutPt(e1, Pt);
            e2->OutIdx = e1->OutIdx;
            e1->Side = esLeft;
            e2->Side = esRight;
            e = e1;
            if (e->PrevInAEL == e2)
                prevE = e2->PrevInAEL;
            else
                prevE = e->PrevInAEL;
        }
        else
        {
            result = AddOutPt(e2, Pt);
            e1->OutIdx = e2->OutIdx;
            e1->Side = esRight;
            e2->Side = esLeft;
            e = e2;
            if (e->PrevInAEL == e1)
                prevE = e1->PrevInAEL;
            else
                prevE = e->PrevInAEL;
        }

        if (prevE && prevE->OutIdx >= 0 && prevE->Top.Y < Pt.Y && e->Top.Y < Pt.Y)
        {
            cInt xPrev = TopX(*prevE, Pt.Y);
            cInt xE = TopX(*e, Pt.Y);
            if (xPrev == xE && (e->WindDelta != 0) && (prevE->WindDelta != 0) &&
                SlopesEqual(IntPoint(xPrev, Pt.Y), prevE->Top, IntPoint(xE, Pt.Y), e->Top, m_UseFullRange))
            {
                OutPt *outPt = AddOutPt(prevE, Pt);
                AddJoin(result, outPt, e->Top);
            }
        }
        return result;
    }
    //------------------------------------------------------------------------------

    void Clipper::AddLocalMaxPoly(TEdge *e1, TEdge *e2, const IntPoint &Pt)
    {
        AddOutPt(e1, Pt);
        if (e2->WindDelta == 0)
            AddOutPt(e2, Pt);
        if (e1->OutIdx == e2->OutIdx)
        {
            e1->OutIdx = Unassigned;
            e2->OutIdx = Unassigned;
        }
        else if (e1->OutIdx < e2->OutIdx)
            AppendPolygon(e1, e2);
        else
            AppendPolygon(e2, e1);
    }
    //------------------------------------------------------------------------------

    void Clipper::AddEdgeToSEL(TEdge *edge)
    {
        // SEL pointers in PEdge are reused to build a list of horizontal edges.
        // However, we don't need to worry about order with horizontal edge processing.
        if (!m_SortedEdges)
        {
            m_SortedEdges = edge;
            edge->PrevInSEL = 0;
            edge->NextInSEL = 0;
        }
        else
        {
            edge->NextInSEL = m_SortedEdges;
            edge->PrevInSEL = 0;
            m_SortedEdges->PrevInSEL = edge;
            m_SortedEdges = edge;
        }
    }
    //------------------------------------------------------------------------------

    bool Clipper::PopEdgeFromSEL(TEdge *&edge)
    {
        if (!m_SortedEdges)
            return false;
        edge = m_SortedEdges;
        DeleteFromSEL(m_SortedEdges);
        return true;
    }
    //------------------------------------------------------------------------------

    void Clipper::CopyAELToSEL()
    {
        TEdge *e = m_ActiveEdges;
        m_SortedEdges = e;
        while (e)
        {
            e->PrevInSEL = e->PrevInAEL;
            e->NextInSEL = e->NextInAEL;
            e = e->NextInAEL;
        }
    }
    //------------------------------------------------------------------------------

    void Clipper::AddJoin(OutPt *op1, OutPt *op2, const IntPoint OffPt)
    {
        Join *j = new Join;
        j->OutPt1 = op1;
        j->OutPt2 = op2;
        j->OffPt = OffPt;
        m_Joins.push_back(j);
    }
    //------------------------------------------------------------------------------

    void Clipper::ClearJoins()
    {
        for (JoinList::size_type i = 0; i < m_Joins.size(); i++)
            delete m_Joins[i];
        m_Joins.resize(0);
    }
    //------------------------------------------------------------------------------

    void Clipper::ClearGhostJoins()
    {
        for (JoinList::size_type i = 0; i < m_GhostJoins.size(); i++)
            delete m_GhostJoins[i];
        m_GhostJoins.resize(0);
    }
    //------------------------------------------------------------------------------

    void Clipper::AddGhostJoin(OutPt *op, const IntPoint OffPt)
    {
        Join *j = new Join;
        j->OutPt1 = op;
        j->OutPt2 = 0;
        j->OffPt = OffPt;
        m_GhostJoins.push_back(j);
    }
    //------------------------------------------------------------------------------

    void Clipper::InsertLocalMinimaIntoAEL(const cInt botY)
    {
        const LocalMinimum *lm;
        while (PopLocalMinima(botY, lm))
        {
            TEdge *lb = lm->LeftBound;
            TEdge *rb = lm->RightBound;

            OutPt *Op1 = 0;
            if (!lb)
            {
                // nb: don't insert LB into either AEL or SEL
                InsertEdgeIntoAEL(rb, 0);
                SetWindingCount(*rb);
                if (IsContributing(*rb))
                    Op1 = AddOutPt(rb, rb->Bot);
            }
            else if (!rb)
            {
                InsertEdgeIntoAEL(lb, 0);
                SetWindingCount(*lb);
                if (IsContributing(*lb))
                    Op1 = AddOutPt(lb, lb->Bot);
                InsertScanbeam(lb->Top.Y);
            }
            else
            {
                InsertEdgeIntoAEL(lb, 0);
                InsertEdgeIntoAEL(rb, lb);
                SetWindingCount(*lb);
                rb->WindCnt = lb->WindCnt;
                rb->WindCnt2 = lb->WindCnt2;
                if (IsContributing(*lb))
                    Op1 = AddLocalMinPoly(lb, rb, lb->Bot);
                InsertScanbeam(lb->Top.Y);
            }

            if (rb)
            {
                if (IsHorizontal(*rb))
                {
                    AddEdgeToSEL(rb);
                    if (rb->NextInLML)
                        InsertScanbeam(rb->NextInLML->Top.Y);
                }
                else
                    InsertScanbeam(rb->Top.Y);
            }

            if (!lb || !rb)
                continue;

            // if any output polygons share an edge, they'll need joining later ...
            if (Op1 && IsHorizontal(*rb) &&
                m_GhostJoins.size() > 0 && (rb->WindDelta != 0))
            {
                for (JoinList::size_type i = 0; i < m_GhostJoins.size(); ++i)
                {
                    Join *jr = m_GhostJoins[i];
                    // if the horizontal Rb and a 'ghost' horizontal overlap, then convert
                    // the 'ghost' join to a real join ready for later ...
                    if (HorzSegmentsOverlap(jr->OutPt1->Pt.X, jr->OffPt.X, rb->Bot.X, rb->Top.X))
                        AddJoin(jr->OutPt1, Op1, jr->OffPt);
                }
            }

            if (lb->OutIdx >= 0 && lb->PrevInAEL &&
                lb->PrevInAEL->Curr.X == lb->Bot.X &&
                lb->PrevInAEL->OutIdx >= 0 &&
                SlopesEqual(lb->PrevInAEL->Bot, lb->PrevInAEL->Top, lb->Curr, lb->Top, m_UseFullRange) &&
                (lb->WindDelta != 0) && (lb->PrevInAEL->WindDelta != 0))
            {
                OutPt *Op2 = AddOutPt(lb->PrevInAEL, lb->Bot);
                AddJoin(Op1, Op2, lb->Top);
            }

            if (lb->NextInAEL != rb)
            {

                if (rb->OutIdx >= 0 && rb->PrevInAEL->OutIdx >= 0 &&
                    SlopesEqual(rb->PrevInAEL->Curr, rb->PrevInAEL->Top, rb->Curr, rb->Top, m_UseFullRange) &&
                    (rb->WindDelta != 0) && (rb->PrevInAEL->WindDelta != 0))
                {
                    OutPt *Op2 = AddOutPt(rb->PrevInAEL, rb->Bot);
                    AddJoin(Op1, Op2, rb->Top);
                }

                TEdge *e = lb->NextInAEL;
                if (e)
                {
                    while (e != rb)
                    {
                        // nb: For calculating winding counts etc, IntersectEdges() assumes
                        // that param1 will be to the Right of param2 ABOVE the intersection ...
                        IntersectEdges(rb, e, lb->Curr); // order important here
                        e = e->NextInAEL;
                    }
                }
            }
        }
    }
    //------------------------------------------------------------------------------

    void Clipper::DeleteFromSEL(TEdge *e)
    {
        TEdge *SelPrev = e->PrevInSEL;
        TEdge *SelNext = e->NextInSEL;
        if (!SelPrev && !SelNext && (e != m_SortedEdges))
            return; // already deleted
        if (SelPrev)
            SelPrev->NextInSEL = SelNext;
        else
            m_SortedEdges = SelNext;
        if (SelNext)
            SelNext->PrevInSEL = SelPrev;
        e->NextInSEL = 0;
        e->PrevInSEL = 0;
    }
    //------------------------------------------------------------------------------

#ifdef use_xyz
    void Clipper::SetZ(IntPoint &pt, TEdge &e1, TEdge &e2)
    {
        if (pt.Z != 0 || !m_ZFill)
            return;
        else if (pt == e1.Bot)
            pt.Z = e1.Bot.Z;
        else if (pt == e1.Top)
            pt.Z = e1.Top.Z;
        else if (pt == e2.Bot)
            pt.Z = e2.Bot.Z;
        else if (pt == e2.Top)
            pt.Z = e2.Top.Z;
        else
            (*m_ZFill)(e1.Bot, e1.Top, e2.Bot, e2.Top, pt);
    }
//------------------------------------------------------------------------------
#endif

    void Clipper::IntersectEdges(TEdge *e1, TEdge *e2, IntPoint &Pt)
    {
        bool e1Contributing = (e1->OutIdx >= 0);
        bool e2Contributing = (e2->OutIdx >= 0);

#ifdef use_xyz
        SetZ(Pt, *e1, *e2);
#endif

#ifdef use_lines
        // if either edge is on an OPEN path ...
        if (e1->WindDelta == 0 || e2->WindDelta == 0)
        {
            // ignore subject-subject open path intersections UNLESS they
            // are both open paths, AND they are both 'contributing maximas' ...
            if (e1->WindDelta == 0 && e2->WindDelta == 0)
                return;

            // if intersecting a subj line with a subj poly ...
            else if (e1->PolyTyp == e2->PolyTyp &&
                     e1->WindDelta != e2->WindDelta && m_ClipType == ctUnion)
            {
                if (e1->WindDelta == 0)
                {
                    if (e2Contributing)
                    {
                        AddOutPt(e1, Pt);
                        if (e1Contributing)
                            e1->OutIdx = Unassigned;
                    }
                }
                else
                {
                    if (e1Contributing)
                    {
                        AddOutPt(e2, Pt);
                        if (e2Contributing)
                            e2->OutIdx = Unassigned;
                    }
                }
            }
            else if (e1->PolyTyp != e2->PolyTyp)
            {
                // toggle subj open path OutIdx on/off when Abs(clip.WndCnt) == 1 ...
                if ((e1->WindDelta == 0) && abs(e2->WindCnt) == 1 &&
                    (m_ClipType != ctUnion || e2->WindCnt2 == 0))
                {
                    AddOutPt(e1, Pt);
                    if (e1Contributing)
                        e1->OutIdx = Unassigned;
                }
                else if ((e2->WindDelta == 0) && (abs(e1->WindCnt) == 1) &&
                         (m_ClipType != ctUnion || e1->WindCnt2 == 0))
                {
                    AddOutPt(e2, Pt);
                    if (e2Contributing)
                        e2->OutIdx = Unassigned;
                }
            }
            return;
        }
#endif

        // update winding counts...
        // assumes that e1 will be to the Right of e2 ABOVE the intersection
        if (e1->PolyTyp == e2->PolyTyp)
        {
            if (IsEvenOddFillType(*e1))
            {
                int oldE1WindCnt = e1->WindCnt;
                e1->WindCnt = e2->WindCnt;
                e2->WindCnt = oldE1WindCnt;
            }
            else
            {
                if (e1->WindCnt + e2->WindDelta == 0)
                    e1->WindCnt = -e1->WindCnt;
                else
                    e1->WindCnt += e2->WindDelta;
                if (e2->WindCnt - e1->WindDelta == 0)
                    e2->WindCnt = -e2->WindCnt;
                else
                    e2->WindCnt -= e1->WindDelta;
            }
        }
        else
        {
            if (!IsEvenOddFillType(*e2))
                e1->WindCnt2 += e2->WindDelta;
            else
                e1->WindCnt2 = (e1->WindCnt2 == 0) ? 1 : 0;
            if (!IsEvenOddFillType(*e1))
                e2->WindCnt2 -= e1->WindDelta;
            else
                e2->WindCnt2 = (e2->WindCnt2 == 0) ? 1 : 0;
        }

        PolyFillType e1FillType, e2FillType, e1FillType2, e2FillType2;
        if (e1->PolyTyp == ptSubject)
        {
            e1FillType = m_SubjFillType;
            e1FillType2 = m_ClipFillType;
        }
        else
        {
            e1FillType = m_ClipFillType;
            e1FillType2 = m_SubjFillType;
        }
        if (e2->PolyTyp == ptSubject)
        {
            e2FillType = m_SubjFillType;
            e2FillType2 = m_ClipFillType;
        }
        else
        {
            e2FillType = m_ClipFillType;
            e2FillType2 = m_SubjFillType;
        }

        cInt e1Wc, e2Wc;
        switch (e1FillType)
        {
        case pftPositive:
            e1Wc = e1->WindCnt;
            break;
        case pftNegative:
            e1Wc = -e1->WindCnt;
            break;
        default:
            e1Wc = Abs(e1->WindCnt);
        }
        switch (e2FillType)
        {
        case pftPositive:
            e2Wc = e2->WindCnt;
            break;
        case pftNegative:
            e2Wc = -e2->WindCnt;
            break;
        default:
            e2Wc = Abs(e2->WindCnt);
        }

        if (e1Contributing && e2Contributing)
        {
            if ((e1Wc != 0 && e1Wc != 1) || (e2Wc != 0 && e2Wc != 1) ||
                (e1->PolyTyp != e2->PolyTyp && m_ClipType != ctXor))
            {
                AddLocalMaxPoly(e1, e2, Pt);
            }
            else
            {
                AddOutPt(e1, Pt);
                AddOutPt(e2, Pt);
                SwapSides(*e1, *e2);
                SwapPolyIndexes(*e1, *e2);
            }
        }
        else if (e1Contributing)
        {
            if (e2Wc == 0 || e2Wc == 1)
            {
                AddOutPt(e1, Pt);
                SwapSides(*e1, *e2);
                SwapPolyIndexes(*e1, *e2);
            }
        }
        else if (e2Contributing)
        {
            if (e1Wc == 0 || e1Wc == 1)
            {
                AddOutPt(e2, Pt);
                SwapSides(*e1, *e2);
                SwapPolyIndexes(*e1, *e2);
            }
        }
        else if ((e1Wc == 0 || e1Wc == 1) && (e2Wc == 0 || e2Wc == 1))
        {
            // neither edge is currently contributing ...

            cInt e1Wc2, e2Wc2;
            switch (e1FillType2)
            {
            case pftPositive:
                e1Wc2 = e1->WindCnt2;
                break;
            case pftNegative:
                e1Wc2 = -e1->WindCnt2;
                break;
            default:
                e1Wc2 = Abs(e1->WindCnt2);
            }
            switch (e2FillType2)
            {
            case pftPositive:
                e2Wc2 = e2->WindCnt2;
                break;
            case pftNegative:
                e2Wc2 = -e2->WindCnt2;
                break;
            default:
                e2Wc2 = Abs(e2->WindCnt2);
            }

            if (e1->PolyTyp != e2->PolyTyp)
            {
                AddLocalMinPoly(e1, e2, Pt);
            }
            else if (e1Wc == 1 && e2Wc == 1)
                switch (m_ClipType)
                {
                case ctIntersection:
                    if (e1Wc2 > 0 && e2Wc2 > 0)
                        AddLocalMinPoly(e1, e2, Pt);
                    break;
                case ctUnion:
                    if (e1Wc2 <= 0 && e2Wc2 <= 0)
                        AddLocalMinPoly(e1, e2, Pt);
                    break;
                case ctDifference:
                    if (((e1->PolyTyp == ptClip) && (e1Wc2 > 0) && (e2Wc2 > 0)) ||
                        ((e1->PolyTyp == ptSubject) && (e1Wc2 <= 0) && (e2Wc2 <= 0)))
                        AddLocalMinPoly(e1, e2, Pt);
                    break;
                case ctXor:
                    AddLocalMinPoly(e1, e2, Pt);
                }
            else
                SwapSides(*e1, *e2);
        }
    }
    //------------------------------------------------------------------------------

    void Clipper::SetHoleState(TEdge *e, OutRec *outrec)
    {
        TEdge *e2 = e->PrevInAEL;
        TEdge *eTmp = 0;
        while (e2)
        {
            if (e2->OutIdx >= 0 && e2->WindDelta != 0)
            {
                if (!eTmp)
                    eTmp = e2;
                else if (eTmp->OutIdx == e2->OutIdx)
                    eTmp = 0;
            }
            e2 = e2->PrevInAEL;
        }
        if (!eTmp)
        {
            outrec->FirstLeft = 0;
            outrec->IsHole = false;
        }
        else
        {
            outrec->FirstLeft = m_PolyOuts[eTmp->OutIdx];
            outrec->IsHole = !outrec->FirstLeft->IsHole;
        }
    }
    //------------------------------------------------------------------------------

    OutRec *GetLowermostRec(OutRec *outRec1, OutRec *outRec2)
    {
        // work out which polygon fragment has the correct hole state ...
        if (!outRec1->BottomPt)
            outRec1->BottomPt = GetBottomPt(outRec1->Pts);
        if (!outRec2->BottomPt)
            outRec2->BottomPt = GetBottomPt(outRec2->Pts);
        OutPt *OutPt1 = outRec1->BottomPt;
        OutPt *OutPt2 = outRec2->BottomPt;
        if (OutPt1->Pt.Y > OutPt2->Pt.Y)
            return outRec1;
        else if (OutPt1->Pt.Y < OutPt2->Pt.Y)
            return outRec2;
        else if (OutPt1->Pt.X < OutPt2->Pt.X)
            return outRec1;
        else if (OutPt1->Pt.X > OutPt2->Pt.X)
            return outRec2;
        else if (OutPt1->Next == OutPt1)
            return outRec2;
        else if (OutPt2->Next == OutPt2)
            return outRec1;
        else if (FirstIsBottomPt(OutPt1, OutPt2))
            return outRec1;
        else
            return outRec2;
    }
    //------------------------------------------------------------------------------

    bool OutRec1RightOfOutRec2(OutRec *outRec1, OutRec *outRec2)
    {
        do
        {
            outRec1 = outRec1->FirstLeft;
            if (outRec1 == outRec2)
                return true;
        } while (outRec1);
        return false;
    }
    //------------------------------------------------------------------------------

    OutRec *Clipper::GetOutRec(int Idx)
    {
        OutRec *outrec = m_PolyOuts[Idx];
        while (outrec != m_PolyOuts[outrec->Idx])
            outrec = m_PolyOuts[outrec->Idx];
        return outrec;
    }
    //------------------------------------------------------------------------------

    void Clipper::AppendPolygon(TEdge *e1, TEdge *e2)
    {
        // get the start and ends of both output polygons ...
        OutRec *outRec1 = m_PolyOuts[e1->OutIdx];
        OutRec *outRec2 = m_PolyOuts[e2->OutIdx];

        OutRec *holeStateRec;
        if (OutRec1RightOfOutRec2(outRec1, outRec2))
            holeStateRec = outRec2;
        else if (OutRec1RightOfOutRec2(outRec2, outRec1))
            holeStateRec = outRec1;
        else
            holeStateRec = GetLowermostRec(outRec1, outRec2);

        // get the start and ends of both output polygons and
        // join e2 poly onto e1 poly and delete pointers to e2 ...

        OutPt *p1_lft = outRec1->Pts;
        OutPt *p1_rt = p1_lft->Prev;
        OutPt *p2_lft = outRec2->Pts;
        OutPt *p2_rt = p2_lft->Prev;

        // join e2 poly onto e1 poly and delete pointers to e2 ...
        if (e1->Side == esLeft)
        {
            if (e2->Side == esLeft)
            {
                // z y x a b c
                ReversePolyPtLinks(p2_lft);
                p2_lft->Next = p1_lft;
                p1_lft->Prev = p2_lft;
                p1_rt->Next = p2_rt;
                p2_rt->Prev = p1_rt;
                outRec1->Pts = p2_rt;
            }
            else
            {
                // x y z a b c
                p2_rt->Next = p1_lft;
                p1_lft->Prev = p2_rt;
                p2_lft->Prev = p1_rt;
                p1_rt->Next = p2_lft;
                outRec1->Pts = p2_lft;
            }
        }
        else
        {
            if (e2->Side == esRight)
            {
                // a b c z y x
                ReversePolyPtLinks(p2_lft);
                p1_rt->Next = p2_rt;
                p2_rt->Prev = p1_rt;
                p2_lft->Next = p1_lft;
                p1_lft->Prev = p2_lft;
            }
            else
            {
                // a b c x y z
                p1_rt->Next = p2_lft;
                p2_lft->Prev = p1_rt;
                p1_lft->Prev = p2_rt;
                p2_rt->Next = p1_lft;
            }
        }

        outRec1->BottomPt = 0;
        if (holeStateRec == outRec2)
        {
            if (outRec2->FirstLeft != outRec1)
                outRec1->FirstLeft = outRec2->FirstLeft;
            outRec1->IsHole = outRec2->IsHole;
        }
        outRec2->Pts = 0;
        outRec2->BottomPt = 0;
        outRec2->FirstLeft = outRec1;

        int OKIdx = e1->OutIdx;
        int ObsoleteIdx = e2->OutIdx;

        e1->OutIdx = Unassigned; // nb: safe because we only get here via AddLocalMaxPoly
        e2->OutIdx = Unassigned;

        TEdge *e = m_ActiveEdges;
        while (e)
        {
            if (e->OutIdx == ObsoleteIdx)
            {
                e->OutIdx = OKIdx;
                e->Side = e1->Side;
                break;
            }
            e = e->NextInAEL;
        }

        outRec2->Idx = outRec1->Idx;
    }
    //------------------------------------------------------------------------------

    OutPt *Clipper::AddOutPt(TEdge *e, const IntPoint &pt)
    {
        if (e->OutIdx < 0)
        {
            OutRec *outRec = CreateOutRec();
            outRec->IsOpen = (e->WindDelta == 0);
            OutPt *newOp = new OutPt;
            outRec->Pts = newOp;
            newOp->Idx = outRec->Idx;
            newOp->Pt = pt;
            newOp->Next = newOp;
            newOp->Prev = newOp;
            if (!outRec->IsOpen)
                SetHoleState(e, outRec);
            e->OutIdx = outRec->Idx;
            return newOp;
        }
        else
        {
            OutRec *outRec = m_PolyOuts[e->OutIdx];
            // OutRec.Pts is the 'Left-most' point & OutRec.Pts.Prev is the 'Right-most'
            OutPt *op = outRec->Pts;

            bool ToFront = (e->Side == esLeft);
            if (ToFront && (pt == op->Pt))
                return op;
            else if (!ToFront && (pt == op->Prev->Pt))
                return op->Prev;

            OutPt *newOp = new OutPt;
            newOp->Idx = outRec->Idx;
            newOp->Pt = pt;
            newOp->Next = op;
            newOp->Prev = op->Prev;
            newOp->Prev->Next = newOp;
            op->Prev = newOp;
            if (ToFront)
                outRec->Pts = newOp;
            return newOp;
        }
    }
    //------------------------------------------------------------------------------

    OutPt *Clipper::GetLastOutPt(TEdge *e)
    {
        OutRec *outRec = m_PolyOuts[e->OutIdx];
        if (e->Side == esLeft)
            return outRec->Pts;
        else
            return outRec->Pts->Prev;
    }
    //------------------------------------------------------------------------------

    void Clipper::ProcessHorizontals()
    {
        TEdge *horzEdge;
        while (PopEdgeFromSEL(horzEdge))
            ProcessHorizontal(horzEdge);
    }
    //------------------------------------------------------------------------------

    inline bool IsMinima(TEdge *e)
    {
        return e && (e->Prev->NextInLML != e) && (e->Next->NextInLML != e);
    }
    //------------------------------------------------------------------------------

    inline bool IsMaxima(TEdge *e, const cInt Y)
    {
        return e && e->Top.Y == Y && !e->NextInLML;
    }
    //------------------------------------------------------------------------------

    inline bool IsIntermediate(TEdge *e, const cInt Y)
    {
        return e->Top.Y == Y && e->NextInLML;
    }
    //------------------------------------------------------------------------------

    TEdge *GetMaximaPair(TEdge *e)
    {
        if ((e->Next->Top == e->Top) && !e->Next->NextInLML)
            return e->Next;
        else if ((e->Prev->Top == e->Top) && !e->Prev->NextInLML)
            return e->Prev;
        else
            return 0;
    }
    //------------------------------------------------------------------------------

    TEdge *GetMaximaPairEx(TEdge *e)
    {
        // as GetMaximaPair() but returns 0 if MaxPair isn't in AEL (unless it's horizontal)
        TEdge *result = GetMaximaPair(e);
        if (result && (result->OutIdx == Skip ||
                       (result->NextInAEL == result->PrevInAEL && !IsHorizontal(*result))))
            return 0;
        return result;
    }
    //------------------------------------------------------------------------------

    void Clipper::SwapPositionsInSEL(TEdge *Edge1, TEdge *Edge2)
    {
        if (!(Edge1->NextInSEL) && !(Edge1->PrevInSEL))
            return;
        if (!(Edge2->NextInSEL) && !(Edge2->PrevInSEL))
            return;

        if (Edge1->NextInSEL == Edge2)
        {
            TEdge *Next = Edge2->NextInSEL;
            if (Next)
                Next->PrevInSEL = Edge1;
            TEdge *Prev = Edge1->PrevInSEL;
            if (Prev)
                Prev->NextInSEL = Edge2;
            Edge2->PrevInSEL = Prev;
            Edge2->NextInSEL = Edge1;
            Edge1->PrevInSEL = Edge2;
            Edge1->NextInSEL = Next;
        }
        else if (Edge2->NextInSEL == Edge1)
        {
            TEdge *Next = Edge1->NextInSEL;
            if (Next)
                Next->PrevInSEL = Edge2;
            TEdge *Prev = Edge2->PrevInSEL;
            if (Prev)
                Prev->NextInSEL = Edge1;
            Edge1->PrevInSEL = Prev;
            Edge1->NextInSEL = Edge2;
            Edge2->PrevInSEL = Edge1;
            Edge2->NextInSEL = Next;
        }
        else
        {
            TEdge *Next = Edge1->NextInSEL;
            TEdge *Prev = Edge1->PrevInSEL;
            Edge1->NextInSEL = Edge2->NextInSEL;
            if (Edge1->NextInSEL)
                Edge1->NextInSEL->PrevInSEL = Edge1;
            Edge1->PrevInSEL = Edge2->PrevInSEL;
            if (Edge1->PrevInSEL)
                Edge1->PrevInSEL->NextInSEL = Edge1;
            Edge2->NextInSEL = Next;
            if (Edge2->NextInSEL)
                Edge2->NextInSEL->PrevInSEL = Edge2;
            Edge2->PrevInSEL = Prev;
            if (Edge2->PrevInSEL)
                Edge2->PrevInSEL->NextInSEL = Edge2;
        }

        if (!Edge1->PrevInSEL)
            m_SortedEdges = Edge1;
        else if (!Edge2->PrevInSEL)
            m_SortedEdges = Edge2;
    }
    //------------------------------------------------------------------------------

    TEdge *GetNextInAEL(TEdge *e, Direction dir)
    {
        return dir == dLeftToRight ? e->NextInAEL : e->PrevInAEL;
    }
    //------------------------------------------------------------------------------

    void GetHorzDirection(TEdge &HorzEdge, Direction &Dir, cInt &Left, cInt &Right)
    {
        if (HorzEdge.Bot.X < HorzEdge.Top.X)
        {
            Left = HorzEdge.Bot.X;
            Right = HorzEdge.Top.X;
            Dir = dLeftToRight;
        }
        else
        {
            Left = HorzEdge.Top.X;
            Right = HorzEdge.Bot.X;
            Dir = dRightToLeft;
        }
    }
    //------------------------------------------------------------------------

    /*******************************************************************************
     * Notes: Horizontal edges (HEs) at scanline intersections (ie at the Top or    *
     * Bottom of a scanbeam) are processed as if layered. The order in which HEs    *
     * are processed doesn't matter. HEs intersect with other HE Bot.Xs only [#]    *
     * (or they could intersect with Top.Xs only, ie EITHER Bot.Xs OR Top.Xs),      *
     * and with other non-horizontal edges [*]. Once these intersections are        *
     * processed, intermediate HEs then 'promote' the Edge above (NextInLML) into   *
     * the AEL. These 'promoted' edges may in turn intersect [%] with other HEs.    *
     *******************************************************************************/

    void Clipper::ProcessHorizontal(TEdge *horzEdge)
    {
        Direction dir;
        cInt horzLeft, horzRight;
        bool IsOpen = (horzEdge->WindDelta == 0);

        GetHorzDirection(*horzEdge, dir, horzLeft, horzRight);

        TEdge *eLastHorz = horzEdge, *eMaxPair = 0;
        while (eLastHorz->NextInLML && IsHorizontal(*eLastHorz->NextInLML))
            eLastHorz = eLastHorz->NextInLML;
        if (!eLastHorz->NextInLML)
            eMaxPair = GetMaximaPair(eLastHorz);

        MaximaList::const_iterator maxIt;
        MaximaList::const_reverse_iterator maxRit;
        if (m_Maxima.size() > 0)
        {
            // get the first maxima in range (X) ...
            if (dir == dLeftToRight)
            {
                maxIt = m_Maxima.begin();
                while (maxIt != m_Maxima.end() && *maxIt <= horzEdge->Bot.X)
                    maxIt++;
                if (maxIt != m_Maxima.end() && *maxIt >= eLastHorz->Top.X)
                    maxIt = m_Maxima.end();
            }
            else
            {
                maxRit = m_Maxima.rbegin();
                while (maxRit != m_Maxima.rend() && *maxRit > horzEdge->Bot.X)
                    maxRit++;
                if (maxRit != m_Maxima.rend() && *maxRit <= eLastHorz->Top.X)
                    maxRit = m_Maxima.rend();
            }
        }

        OutPt *op1 = 0;

        for (;;) // loop through consec. horizontal edges
        {

            bool IsLastHorz = (horzEdge == eLastHorz);
            TEdge *e = GetNextInAEL(horzEdge, dir);
            while (e)
            {

                // this code block inserts extra coords into horizontal edges (in output
                // polygons) whereever maxima touch these horizontal edges. This helps
                //'simplifying' polygons (ie if the Simplify property is set).
                if (m_Maxima.size() > 0)
                {
                    if (dir == dLeftToRight)
                    {
                        while (maxIt != m_Maxima.end() && *maxIt < e->Curr.X)
                        {
                            if (horzEdge->OutIdx >= 0 && !IsOpen)
                                AddOutPt(horzEdge, IntPoint(*maxIt, horzEdge->Bot.Y));
                            maxIt++;
                        }
                    }
                    else
                    {
                        while (maxRit != m_Maxima.rend() && *maxRit > e->Curr.X)
                        {
                            if (horzEdge->OutIdx >= 0 && !IsOpen)
                                AddOutPt(horzEdge, IntPoint(*maxRit, horzEdge->Bot.Y));
                            maxRit++;
                        }
                    }
                };

                if ((dir == dLeftToRight && e->Curr.X > horzRight) ||
                    (dir == dRightToLeft && e->Curr.X < horzLeft))
                    break;

                // Also break if we've got to the end of an intermediate horizontal edge ...
                // nb: Smaller Dx's are to the right of larger Dx's ABOVE the horizontal.
                if (e->Curr.X == horzEdge->Top.X && horzEdge->NextInLML &&
                    e->Dx < horzEdge->NextInLML->Dx)
                    break;

                if (horzEdge->OutIdx >= 0 && !IsOpen) // note: may be done multiple times
                {
#ifdef use_xyz
                    if (dir == dLeftToRight)
                        SetZ(e->Curr, *horzEdge, *e);
                    else
                        SetZ(e->Curr, *e, *horzEdge);
#endif
                    op1 = AddOutPt(horzEdge, e->Curr);
                    TEdge *eNextHorz = m_SortedEdges;
                    while (eNextHorz)
                    {
                        if (eNextHorz->OutIdx >= 0 &&
                            HorzSegmentsOverlap(horzEdge->Bot.X,
                                                horzEdge->Top.X, eNextHorz->Bot.X, eNextHorz->Top.X))
                        {
                            OutPt *op2 = GetLastOutPt(eNextHorz);
                            AddJoin(op2, op1, eNextHorz->Top);
                        }
                        eNextHorz = eNextHorz->NextInSEL;
                    }
                    AddGhostJoin(op1, horzEdge->Bot);
                }

                // OK, so far we're still in range of the horizontal Edge  but make sure
                // we're at the last of consec. horizontals when matching with eMaxPair
                if (e == eMaxPair && IsLastHorz)
                {
                    if (horzEdge->OutIdx >= 0)
                        AddLocalMaxPoly(horzEdge, eMaxPair, horzEdge->Top);
                    DeleteFromAEL(horzEdge);
                    DeleteFromAEL(eMaxPair);
                    return;
                }

                if (dir == dLeftToRight)
                {
                    IntPoint Pt = IntPoint(e->Curr.X, horzEdge->Curr.Y);
                    IntersectEdges(horzEdge, e, Pt);
                }
                else
                {
                    IntPoint Pt = IntPoint(e->Curr.X, horzEdge->Curr.Y);
                    IntersectEdges(e, horzEdge, Pt);
                }
                TEdge *eNext = GetNextInAEL(e, dir);
                SwapPositionsInAEL(horzEdge, e);
                e = eNext;
            } // end while(e)

            // Break out of loop if HorzEdge.NextInLML is not also horizontal ...
            if (!horzEdge->NextInLML || !IsHorizontal(*horzEdge->NextInLML))
                break;

            UpdateEdgeIntoAEL(horzEdge);
            if (horzEdge->OutIdx >= 0)
                AddOutPt(horzEdge, horzEdge->Bot);
            GetHorzDirection(*horzEdge, dir, horzLeft, horzRight);

        } // end for (;;)

        if (horzEdge->OutIdx >= 0 && !op1)
        {
            op1 = GetLastOutPt(horzEdge);
            TEdge *eNextHorz = m_SortedEdges;
            while (eNextHorz)
            {
                if (eNextHorz->OutIdx >= 0 &&
                    HorzSegmentsOverlap(horzEdge->Bot.X,
                                        horzEdge->Top.X, eNextHorz->Bot.X, eNextHorz->Top.X))
                {
                    OutPt *op2 = GetLastOutPt(eNextHorz);
                    AddJoin(op2, op1, eNextHorz->Top);
                }
                eNextHorz = eNextHorz->NextInSEL;
            }
            AddGhostJoin(op1, horzEdge->Top);
        }

        if (horzEdge->NextInLML)
        {
            if (horzEdge->OutIdx >= 0)
            {
                op1 = AddOutPt(horzEdge, horzEdge->Top);
                UpdateEdgeIntoAEL(horzEdge);
                if (horzEdge->WindDelta == 0)
                    return;
                // nb: HorzEdge is no longer horizontal here
                TEdge *ePrev = horzEdge->PrevInAEL;
                TEdge *eNext = horzEdge->NextInAEL;
                if (ePrev && ePrev->Curr.X == horzEdge->Bot.X &&
                    ePrev->Curr.Y == horzEdge->Bot.Y && ePrev->WindDelta != 0 &&
                    (ePrev->OutIdx >= 0 && ePrev->Curr.Y > ePrev->Top.Y &&
                     SlopesEqual(*horzEdge, *ePrev, m_UseFullRange)))
                {
                    OutPt *op2 = AddOutPt(ePrev, horzEdge->Bot);
                    AddJoin(op1, op2, horzEdge->Top);
                }
                else if (eNext && eNext->Curr.X == horzEdge->Bot.X &&
                         eNext->Curr.Y == horzEdge->Bot.Y && eNext->WindDelta != 0 &&
                         eNext->OutIdx >= 0 && eNext->Curr.Y > eNext->Top.Y &&
                         SlopesEqual(*horzEdge, *eNext, m_UseFullRange))
                {
                    OutPt *op2 = AddOutPt(eNext, horzEdge->Bot);
                    AddJoin(op1, op2, horzEdge->Top);
                }
            }
            else
                UpdateEdgeIntoAEL(horzEdge);
        }
        else
        {
            if (horzEdge->OutIdx >= 0)
                AddOutPt(horzEdge, horzEdge->Top);
            DeleteFromAEL(horzEdge);
        }
    }
    //------------------------------------------------------------------------------

    bool Clipper::ProcessIntersections(const cInt topY)
    {
        if (!m_ActiveEdges)
            return true;
        // try
        {
            BuildIntersectList(topY);
            size_t IlSize = m_IntersectList.size();
            if (IlSize == 0)
                return true;
            if (IlSize == 1 || FixupIntersectionOrder())
                ProcessIntersectList();
            else
                return false;
        }
        // catch(...)
        //{
        //     m_SortedEdges = 0;
        //     DisposeIntersectNodes();
        //     throw clipperException("ProcessIntersections error");
        // }
        m_SortedEdges = 0;
        return true;
    }
    //------------------------------------------------------------------------------

    void Clipper::DisposeIntersectNodes()
    {
        for (size_t i = 0; i < m_IntersectList.size(); ++i)
            delete m_IntersectList[i];
        m_IntersectList.clear();
    }
    //------------------------------------------------------------------------------

    void Clipper::BuildIntersectList(const cInt topY)
    {
        if (!m_ActiveEdges)
            return;

        // prepare for sorting ...
        TEdge *e = m_ActiveEdges;
        m_SortedEdges = e;
        while (e)
        {
            e->PrevInSEL = e->PrevInAEL;
            e->NextInSEL = e->NextInAEL;
            e->Curr.X = TopX(*e, topY);
            e = e->NextInAEL;
        }

        // bubblesort ...
        bool isModified;
        do
        {
            isModified = false;
            e = m_SortedEdges;
            while (e->NextInSEL)
            {
                TEdge *eNext = e->NextInSEL;
                IntPoint Pt;
                if (e->Curr.X > eNext->Curr.X)
                {
                    IntersectPoint(*e, *eNext, Pt);
                    if (Pt.Y < topY)
                        Pt = IntPoint(TopX(*e, topY), topY);
                    IntersectNode *newNode = new IntersectNode;
                    newNode->Edge1 = e;
                    newNode->Edge2 = eNext;
                    newNode->Pt = Pt;
                    m_IntersectList.push_back(newNode);

                    SwapPositionsInSEL(e, eNext);
                    isModified = true;
                }
                else
                    e = eNext;
            }
            if (e->PrevInSEL)
                e->PrevInSEL->NextInSEL = 0;
            else
                break;
        } while (isModified);
        m_SortedEdges = 0; // important
    }
    //------------------------------------------------------------------------------

    void Clipper::ProcessIntersectList()
    {
        for (size_t i = 0; i < m_IntersectList.size(); ++i)
        {
            IntersectNode *iNode = m_IntersectList[i];
            {
                IntersectEdges(iNode->Edge1, iNode->Edge2, iNode->Pt);
                SwapPositionsInAEL(iNode->Edge1, iNode->Edge2);
            }
            delete iNode;
        }
        m_IntersectList.clear();
    }
    //------------------------------------------------------------------------------

    bool IntersectListSort(IntersectNode *node1, IntersectNode *node2)
    {
        return node2->Pt.Y < node1->Pt.Y;
    }
    //------------------------------------------------------------------------------

    inline bool EdgesAdjacent(const IntersectNode &inode)
    {
        return (inode.Edge1->NextInSEL == inode.Edge2) ||
               (inode.Edge1->PrevInSEL == inode.Edge2);
    }
    //------------------------------------------------------------------------------

    bool Clipper::FixupIntersectionOrder()
    {
        // pre-condition: intersections are sorted Bottom-most first.
        // Now it's crucial that intersections are made only between adjacent edges,
        // so to ensure this the order of intersections may need adjusting ...
        CopyAELToSEL();
        std::sort(m_IntersectList.begin(), m_IntersectList.end(), IntersectListSort);
        size_t cnt = m_IntersectList.size();
        for (size_t i = 0; i < cnt; ++i)
        {
            if (!EdgesAdjacent(*m_IntersectList[i]))
            {
                size_t j = i + 1;
                while (j < cnt && !EdgesAdjacent(*m_IntersectList[j]))
                    j++;
                if (j == cnt)
                    return false;
                std::swap(m_IntersectList[i], m_IntersectList[j]);
            }
            SwapPositionsInSEL(m_IntersectList[i]->Edge1, m_IntersectList[i]->Edge2);
        }
        return true;
    }
    //------------------------------------------------------------------------------

    void Clipper::DoMaxima(TEdge *e)
    {
        TEdge *eMaxPair = GetMaximaPairEx(e);
        if (!eMaxPair)
        {
            if (e->OutIdx >= 0)
                AddOutPt(e, e->Top);
            DeleteFromAEL(e);
            return;
        }

        TEdge *eNext = e->NextInAEL;
        while (eNext && eNext != eMaxPair)
        {
            IntersectEdges(e, eNext, e->Top);
            SwapPositionsInAEL(e, eNext);
            eNext = e->NextInAEL;
        }

        if (e->OutIdx == Unassigned && eMaxPair->OutIdx == Unassigned)
        {
            DeleteFromAEL(e);
            DeleteFromAEL(eMaxPair);
        }
        else if (e->OutIdx >= 0 && eMaxPair->OutIdx >= 0)
        {
            if (e->OutIdx >= 0)
                AddLocalMaxPoly(e, eMaxPair, e->Top);
            DeleteFromAEL(e);
            DeleteFromAEL(eMaxPair);
        }
#ifdef use_lines
        else if (e->WindDelta == 0)
        {
            if (e->OutIdx >= 0)
            {
                AddOutPt(e, e->Top);
                e->OutIdx = Unassigned;
            }
            DeleteFromAEL(e);

            if (eMaxPair->OutIdx >= 0)
            {
                AddOutPt(eMaxPair, e->Top);
                eMaxPair->OutIdx = Unassigned;
            }
            DeleteFromAEL(eMaxPair);
        }
#endif
        else
            return; // throw clipperException("DoMaxima error");
    }
    //------------------------------------------------------------------------------

    void Clipper::ProcessEdgesAtTopOfScanbeam(const cInt topY)
    {
        TEdge *e = m_ActiveEdges;
        while (e)
        {
            // 1. process maxima, treating them as if they're 'bent' horizontal edges,
            //    but exclude maxima with horizontal edges. nb: e can't be a horizontal.
            bool IsMaximaEdge = IsMaxima(e, topY);

            if (IsMaximaEdge)
            {
                TEdge *eMaxPair = GetMaximaPairEx(e);
                IsMaximaEdge = (!eMaxPair || !IsHorizontal(*eMaxPair));
            }

            if (IsMaximaEdge)
            {
                if (m_StrictSimple)
                    m_Maxima.push_back(e->Top.X);
                TEdge *ePrev = e->PrevInAEL;
                DoMaxima(e);
                if (!ePrev)
                    e = m_ActiveEdges;
                else
                    e = ePrev->NextInAEL;
            }
            else
            {
                // 2. promote horizontal edges, otherwise update Curr.X and Curr.Y ...
                if (IsIntermediate(e, topY) && IsHorizontal(*e->NextInLML))
                {
                    UpdateEdgeIntoAEL(e);
                    if (e->OutIdx >= 0)
                        AddOutPt(e, e->Bot);
                    AddEdgeToSEL(e);
                }
                else
                {
                    e->Curr.X = TopX(*e, topY);
                    e->Curr.Y = topY;
#ifdef use_xyz
                    e->Curr.Z = topY == e->Top.Y ? e->Top.Z : (topY == e->Bot.Y ? e->Bot.Z : 0);
#endif
                }

                // When StrictlySimple and 'e' is being touched by another edge, then
                // make sure both edges have a vertex here ...
                if (m_StrictSimple)
                {
                    TEdge *ePrev = e->PrevInAEL;
                    if ((e->OutIdx >= 0) && (e->WindDelta != 0) && ePrev && (ePrev->OutIdx >= 0) &&
                        (ePrev->Curr.X == e->Curr.X) && (ePrev->WindDelta != 0))
                    {
                        IntPoint pt = e->Curr;
#ifdef use_xyz
                        SetZ(pt, *ePrev, *e);
#endif
                        OutPt *op = AddOutPt(ePrev, pt);
                        OutPt *op2 = AddOutPt(e, pt);
                        AddJoin(op, op2, pt); // StrictlySimple (type-3) join
                    }
                }

                e = e->NextInAEL;
            }
        }

        // 3. Process horizontals at the Top of the scanbeam ...
        m_Maxima.sort();
        ProcessHorizontals();
        m_Maxima.clear();

        // 4. Promote intermediate vertices ...
        e = m_ActiveEdges;
        while (e)
        {
            if (IsIntermediate(e, topY))
            {
                OutPt *op = 0;
                if (e->OutIdx >= 0)
                    op = AddOutPt(e, e->Top);
                UpdateEdgeIntoAEL(e);

                // if output polygons share an edge, they'll need joining later ...
                TEdge *ePrev = e->PrevInAEL;
                TEdge *eNext = e->NextInAEL;
                if (ePrev && ePrev->Curr.X == e->Bot.X &&
                    ePrev->Curr.Y == e->Bot.Y && op &&
                    ePrev->OutIdx >= 0 && ePrev->Curr.Y > ePrev->Top.Y &&
                    SlopesEqual(e->Curr, e->Top, ePrev->Curr, ePrev->Top, m_UseFullRange) &&
                    (e->WindDelta != 0) && (ePrev->WindDelta != 0))
                {
                    OutPt *op2 = AddOutPt(ePrev, e->Bot);
                    AddJoin(op, op2, e->Top);
                }
                else if (eNext && eNext->Curr.X == e->Bot.X &&
                         eNext->Curr.Y == e->Bot.Y && op &&
                         eNext->OutIdx >= 0 && eNext->Curr.Y > eNext->Top.Y &&
                         SlopesEqual(e->Curr, e->Top, eNext->Curr, eNext->Top, m_UseFullRange) &&
                         (e->WindDelta != 0) && (eNext->WindDelta != 0))
                {
                    OutPt *op2 = AddOutPt(eNext, e->Bot);
                    AddJoin(op, op2, e->Top);
                }
            }
            e = e->NextInAEL;
        }
    }
    //------------------------------------------------------------------------------

    void Clipper::FixupOutPolyline(OutRec &outrec)
    {
        OutPt *pp = outrec.Pts;
        OutPt *lastPP = pp->Prev;
        while (pp != lastPP)
        {
            pp = pp->Next;
            if (pp->Pt == pp->Prev->Pt)
            {
                if (pp == lastPP)
                    lastPP = pp->Prev;
                OutPt *tmpPP = pp->Prev;
                tmpPP->Next = pp->Next;
                pp->Next->Prev = tmpPP;
                delete pp;
                pp = tmpPP;
            }
        }

        if (pp == pp->Prev)
        {
            DisposeOutPts(pp);
            outrec.Pts = 0;
            return;
        }
    }
    //------------------------------------------------------------------------------

    void Clipper::FixupOutPolygon(OutRec &outrec)
    {
        // FixupOutPolygon() - removes duplicate points and simplifies consecutive
        // parallel edges by removing the middle vertex.
        OutPt *lastOK = 0;
        outrec.BottomPt = 0;
        OutPt *pp = outrec.Pts;
        bool preserveCol = m_PreserveCollinear || m_StrictSimple;

        for (;;)
        {
            if (pp->Prev == pp || pp->Prev == pp->Next)
            {
                DisposeOutPts(pp);
                outrec.Pts = 0;
                return;
            }

            // test for duplicate points and collinear edges ...
            if ((pp->Pt == pp->Next->Pt) || (pp->Pt == pp->Prev->Pt) ||
                (SlopesEqual(pp->Prev->Pt, pp->Pt, pp->Next->Pt, m_UseFullRange) &&
                 (!preserveCol || !Pt2IsBetweenPt1AndPt3(pp->Prev->Pt, pp->Pt, pp->Next->Pt))))
            {
                lastOK = 0;
                OutPt *tmp = pp;
                pp->Prev->Next = pp->Next;
                pp->Next->Prev = pp->Prev;
                pp = pp->Prev;
                delete tmp;
            }
            else if (pp == lastOK)
                break;
            else
            {
                if (!lastOK)
                    lastOK = pp;
                pp = pp->Next;
            }
        }
        outrec.Pts = pp;
    }
    //------------------------------------------------------------------------------

    int PointCount(OutPt *Pts)
    {
        if (!Pts)
            return 0;
        int result = 0;
        OutPt *p = Pts;
        do
        {
            result++;
            p = p->Next;
        } while (p != Pts);
        return result;
    }
    //------------------------------------------------------------------------------

    void Clipper::BuildResult(Paths &polys)
    {
        polys.reserve(m_PolyOuts.size());
        for (PolyOutList::size_type i = 0; i < m_PolyOuts.size(); ++i)
        {
            if (!m_PolyOuts[i]->Pts)
                continue;
            Path pg;
            OutPt *p = m_PolyOuts[i]->Pts->Prev;
            int cnt = PointCount(p);
            if (cnt < 2)
                continue;
            pg.reserve(cnt);
            for (int i = 0; i < cnt; ++i)
            {
                pg.push_back(p->Pt);
                p = p->Prev;
            }
            polys.push_back(pg);
        }
    }
    //------------------------------------------------------------------------------

    void Clipper::BuildResult2(PolyTree &polytree)
    {
        polytree.Clear();
        polytree.AllNodes.reserve(m_PolyOuts.size());
        // add each output polygon/contour to polytree ...
        for (PolyOutList::size_type i = 0; i < m_PolyOuts.size(); i++)
        {
            OutRec *outRec = m_PolyOuts[i];
            int cnt = PointCount(outRec->Pts);
            if ((outRec->IsOpen && cnt < 2) || (!outRec->IsOpen && cnt < 3))
                continue;
            FixHoleLinkage(*outRec);
            PolyNode *pn = new PolyNode();
            // nb: polytree takes ownership of all the PolyNodes
            polytree.AllNodes.push_back(pn);
            outRec->PolyNd = pn;
            pn->Parent = 0;
            pn->Index = 0;
            pn->Contour.reserve(cnt);
            OutPt *op = outRec->Pts->Prev;
            for (int j = 0; j < cnt; j++)
            {
                pn->Contour.push_back(op->Pt);
                op = op->Prev;
            }
        }

        // fixup PolyNode links etc ...
        polytree.Childs.reserve(m_PolyOuts.size());
        for (PolyOutList::size_type i = 0; i < m_PolyOuts.size(); i++)
        {
            OutRec *outRec = m_PolyOuts[i];
            if (!outRec->PolyNd)
                continue;
            if (outRec->IsOpen)
            {
                outRec->PolyNd->m_IsOpen = true;
                polytree.AddChild(*outRec->PolyNd);
            }
            else if (outRec->FirstLeft && outRec->FirstLeft->PolyNd)
                outRec->FirstLeft->PolyNd->AddChild(*outRec->PolyNd);
            else
                polytree.AddChild(*outRec->PolyNd);
        }
    }
    //------------------------------------------------------------------------------

    void SwapIntersectNodes(IntersectNode &int1, IntersectNode &int2)
    {
        // just swap the contents (because fIntersectNodes is a single-linked-list)
        IntersectNode inode = int1; // gets a copy of Int1
        int1.Edge1 = int2.Edge1;
        int1.Edge2 = int2.Edge2;
        int1.Pt = int2.Pt;
        int2.Edge1 = inode.Edge1;
        int2.Edge2 = inode.Edge2;
        int2.Pt = inode.Pt;
    }
    //------------------------------------------------------------------------------

    inline bool E2InsertsBeforeE1(TEdge &e1, TEdge &e2)
    {
        if (e2.Curr.X == e1.Curr.X)
        {
            if (e2.Top.Y > e1.Top.Y)
                return e2.Top.X < TopX(e1, e2.Top.Y);
            else
                return e1.Top.X > TopX(e2, e1.Top.Y);
        }
        else
            return e2.Curr.X < e1.Curr.X;
    }
    //------------------------------------------------------------------------------

    bool GetOverlap(const cInt a1, const cInt a2, const cInt b1, const cInt b2,
                    cInt &Left, cInt &Right)
    {
        if (a1 < a2)
        {
            if (b1 < b2)
            {
                Left = std::max(a1, b1);
                Right = std::min(a2, b2);
            }
            else
            {
                Left = std::max(a1, b2);
                Right = std::min(a2, b1);
            }
        }
        else
        {
            if (b1 < b2)
            {
                Left = std::max(a2, b1);
                Right = std::min(a1, b2);
            }
            else
            {
                Left = std::max(a2, b2);
                Right = std::min(a1, b1);
            }
        }
        return Left < Right;
    }
    //------------------------------------------------------------------------------

    inline void UpdateOutPtIdxs(OutRec &outrec)
    {
        OutPt *op = outrec.Pts;
        do
        {
            op->Idx = outrec.Idx;
            op = op->Prev;
        } while (op != outrec.Pts);
    }
    //------------------------------------------------------------------------------

    void Clipper::InsertEdgeIntoAEL(TEdge *edge, TEdge *startEdge)
    {
        if (!m_ActiveEdges)
        {
            edge->PrevInAEL = 0;
            edge->NextInAEL = 0;
            m_ActiveEdges = edge;
        }
        else if (!startEdge && E2InsertsBeforeE1(*m_ActiveEdges, *edge))
        {
            edge->PrevInAEL = 0;
            edge->NextInAEL = m_ActiveEdges;
            m_ActiveEdges->PrevInAEL = edge;
            m_ActiveEdges = edge;
        }
        else
        {
            if (!startEdge)
                startEdge = m_ActiveEdges;
            while (startEdge->NextInAEL &&
                   !E2InsertsBeforeE1(*startEdge->NextInAEL, *edge))
                startEdge = startEdge->NextInAEL;
            edge->NextInAEL = startEdge->NextInAEL;
            if (startEdge->NextInAEL)
                startEdge->NextInAEL->PrevInAEL = edge;
            edge->PrevInAEL = startEdge;
            startEdge->NextInAEL = edge;
        }
    }
    //----------------------------------------------------------------------

    OutPt *DupOutPt(OutPt *outPt, bool InsertAfter)
    {
        OutPt *result = new OutPt;
        result->Pt = outPt->Pt;
        result->Idx = outPt->Idx;
        if (InsertAfter)
        {
            result->Next = outPt->Next;
            result->Prev = outPt;
            outPt->Next->Prev = result;
            outPt->Next = result;
        }
        else
        {
            result->Prev = outPt->Prev;
            result->Next = outPt;
            outPt->Prev->Next = result;
            outPt->Prev = result;
        }
        return result;
    }
    //------------------------------------------------------------------------------

    bool JoinHorz(OutPt *op1, OutPt *op1b, OutPt *op2, OutPt *op2b,
                  const IntPoint Pt, bool DiscardLeft)
    {
        Direction Dir1 = (op1->Pt.X > op1b->Pt.X ? dRightToLeft : dLeftToRight);
        Direction Dir2 = (op2->Pt.X > op2b->Pt.X ? dRightToLeft : dLeftToRight);
        if (Dir1 == Dir2)
            return false;

        // When DiscardLeft, we want Op1b to be on the Left of Op1, otherwise we
        // want Op1b to be on the Right. (And likewise with Op2 and Op2b.)
        // So, to facilitate this while inserting Op1b and Op2b ...
        // when DiscardLeft, make sure we're AT or RIGHT of Pt before adding Op1b,
        // otherwise make sure we're AT or LEFT of Pt. (Likewise with Op2b.)
        if (Dir1 == dLeftToRight)
        {
            while (op1->Next->Pt.X <= Pt.X &&
                   op1->Next->Pt.X >= op1->Pt.X && op1->Next->Pt.Y == Pt.Y)
                op1 = op1->Next;
            if (DiscardLeft && (op1->Pt.X != Pt.X))
                op1 = op1->Next;
            op1b = DupOutPt(op1, !DiscardLeft);
            if (op1b->Pt != Pt)
            {
                op1 = op1b;
                op1->Pt = Pt;
                op1b = DupOutPt(op1, !DiscardLeft);
            }
        }
        else
        {
            while (op1->Next->Pt.X >= Pt.X &&
                   op1->Next->Pt.X <= op1->Pt.X && op1->Next->Pt.Y == Pt.Y)
                op1 = op1->Next;
            if (!DiscardLeft && (op1->Pt.X != Pt.X))
                op1 = op1->Next;
            op1b = DupOutPt(op1, DiscardLeft);
            if (op1b->Pt != Pt)
            {
                op1 = op1b;
                op1->Pt = Pt;
                op1b = DupOutPt(op1, DiscardLeft);
            }
        }

        if (Dir2 == dLeftToRight)
        {
            while (op2->Next->Pt.X <= Pt.X &&
                   op2->Next->Pt.X >= op2->Pt.X && op2->Next->Pt.Y == Pt.Y)
                op2 = op2->Next;
            if (DiscardLeft && (op2->Pt.X != Pt.X))
                op2 = op2->Next;
            op2b = DupOutPt(op2, !DiscardLeft);
            if (op2b->Pt != Pt)
            {
                op2 = op2b;
                op2->Pt = Pt;
                op2b = DupOutPt(op2, !DiscardLeft);
            };
        }
        else
        {
            while (op2->Next->Pt.X >= Pt.X &&
                   op2->Next->Pt.X <= op2->Pt.X && op2->Next->Pt.Y == Pt.Y)
                op2 = op2->Next;
            if (!DiscardLeft && (op2->Pt.X != Pt.X))
                op2 = op2->Next;
            op2b = DupOutPt(op2, DiscardLeft);
            if (op2b->Pt != Pt)
            {
                op2 = op2b;
                op2->Pt = Pt;
                op2b = DupOutPt(op2, DiscardLeft);
            };
        };

        if ((Dir1 == dLeftToRight) == DiscardLeft)
        {
            op1->Prev = op2;
            op2->Next = op1;
            op1b->Next = op2b;
            op2b->Prev = op1b;
        }
        else
        {
            op1->Next = op2;
            op2->Prev = op1;
            op1b->Prev = op2b;
            op2b->Next = op1b;
        }
        return true;
    }
    //------------------------------------------------------------------------------

    bool Clipper::JoinPoints(Join *j, OutRec *outRec1, OutRec *outRec2)
    {
        OutPt *op1 = j->OutPt1, *op1b;
        OutPt *op2 = j->OutPt2, *op2b;

        // There are 3 kinds of joins for output polygons ...
        // 1. Horizontal joins where Join.OutPt1 & Join.OutPt2 are vertices anywhere
        // along (horizontal) collinear edges (& Join.OffPt is on the same horizontal).
        // 2. Non-horizontal joins where Join.OutPt1 & Join.OutPt2 are at the same
        // location at the Bottom of the overlapping segment (& Join.OffPt is above).
        // 3. StrictSimple joins where edges touch but are not collinear and where
        // Join.OutPt1, Join.OutPt2 & Join.OffPt all share the same point.
        bool isHorizontal = (j->OutPt1->Pt.Y == j->OffPt.Y);

        if (isHorizontal && (j->OffPt == j->OutPt1->Pt) &&
            (j->OffPt == j->OutPt2->Pt))
        {
            // Strictly Simple join ...
            if (outRec1 != outRec2)
                return false;
            op1b = j->OutPt1->Next;
            while (op1b != op1 && (op1b->Pt == j->OffPt))
                op1b = op1b->Next;
            bool reverse1 = (op1b->Pt.Y > j->OffPt.Y);
            op2b = j->OutPt2->Next;
            while (op2b != op2 && (op2b->Pt == j->OffPt))
                op2b = op2b->Next;
            bool reverse2 = (op2b->Pt.Y > j->OffPt.Y);
            if (reverse1 == reverse2)
                return false;
            if (reverse1)
            {
                op1b = DupOutPt(op1, false);
                op2b = DupOutPt(op2, true);
                op1->Prev = op2;
                op2->Next = op1;
                op1b->Next = op2b;
                op2b->Prev = op1b;
                j->OutPt1 = op1;
                j->OutPt2 = op1b;
                return true;
            }
            else
            {
                op1b = DupOutPt(op1, true);
                op2b = DupOutPt(op2, false);
                op1->Next = op2;
                op2->Prev = op1;
                op1b->Prev = op2b;
                op2b->Next = op1b;
                j->OutPt1 = op1;
                j->OutPt2 = op1b;
                return true;
            }
        }
        else if (isHorizontal)
        {
            // treat horizontal joins differently to non-horizontal joins since with
            // them we're not yet sure where the overlapping is. OutPt1.Pt & OutPt2.Pt
            // may be anywhere along the horizontal edge.
            op1b = op1;
            while (op1->Prev->Pt.Y == op1->Pt.Y && op1->Prev != op1b && op1->Prev != op2)
                op1 = op1->Prev;
            while (op1b->Next->Pt.Y == op1b->Pt.Y && op1b->Next != op1 && op1b->Next != op2)
                op1b = op1b->Next;
            if (op1b->Next == op1 || op1b->Next == op2)
                return false; // a flat 'polygon'

            op2b = op2;
            while (op2->Prev->Pt.Y == op2->Pt.Y && op2->Prev != op2b && op2->Prev != op1b)
                op2 = op2->Prev;
            while (op2b->Next->Pt.Y == op2b->Pt.Y && op2b->Next != op2 && op2b->Next != op1)
                op2b = op2b->Next;
            if (op2b->Next == op2 || op2b->Next == op1)
                return false; // a flat 'polygon'

            cInt Left, Right;
            // Op1 --> Op1b & Op2 --> Op2b are the extremites of the horizontal edges
            if (!GetOverlap(op1->Pt.X, op1b->Pt.X, op2->Pt.X, op2b->Pt.X, Left, Right))
                return false;

            // DiscardLeftSide: when overlapping edges are joined, a spike will created
            // which needs to be cleaned up. However, we don't want Op1 or Op2 caught up
            // on the discard Side as either may still be needed for other joins ...
            IntPoint Pt;
            bool DiscardLeftSide;
            if (op1->Pt.X >= Left && op1->Pt.X <= Right)
            {
                Pt = op1->Pt;
                DiscardLeftSide = (op1->Pt.X > op1b->Pt.X);
            }
            else if (op2->Pt.X >= Left && op2->Pt.X <= Right)
            {
                Pt = op2->Pt;
                DiscardLeftSide = (op2->Pt.X > op2b->Pt.X);
            }
            else if (op1b->Pt.X >= Left && op1b->Pt.X <= Right)
            {
                Pt = op1b->Pt;
                DiscardLeftSide = op1b->Pt.X > op1->Pt.X;
            }
            else
            {
                Pt = op2b->Pt;
                DiscardLeftSide = (op2b->Pt.X > op2->Pt.X);
            }
            j->OutPt1 = op1;
            j->OutPt2 = op2;
            return JoinHorz(op1, op1b, op2, op2b, Pt, DiscardLeftSide);
        }
        else
        {
            // nb: For non-horizontal joins ...
            //     1. Jr.OutPt1.Pt.Y == Jr.OutPt2.Pt.Y
            //     2. Jr.OutPt1.Pt > Jr.OffPt.Y

            // make sure the polygons are correctly oriented ...
            op1b = op1->Next;
            while ((op1b->Pt == op1->Pt) && (op1b != op1))
                op1b = op1b->Next;
            bool Reverse1 = ((op1b->Pt.Y > op1->Pt.Y) ||
                             !SlopesEqual(op1->Pt, op1b->Pt, j->OffPt, m_UseFullRange));
            if (Reverse1)
            {
                op1b = op1->Prev;
                while ((op1b->Pt == op1->Pt) && (op1b != op1))
                    op1b = op1b->Prev;
                if ((op1b->Pt.Y > op1->Pt.Y) ||
                    !SlopesEqual(op1->Pt, op1b->Pt, j->OffPt, m_UseFullRange))
                    return false;
            };
            op2b = op2->Next;
            while ((op2b->Pt == op2->Pt) && (op2b != op2))
                op2b = op2b->Next;
            bool Reverse2 = ((op2b->Pt.Y > op2->Pt.Y) ||
                             !SlopesEqual(op2->Pt, op2b->Pt, j->OffPt, m_UseFullRange));
            if (Reverse2)
            {
                op2b = op2->Prev;
                while ((op2b->Pt == op2->Pt) && (op2b != op2))
                    op2b = op2b->Prev;
                if ((op2b->Pt.Y > op2->Pt.Y) ||
                    !SlopesEqual(op2->Pt, op2b->Pt, j->OffPt, m_UseFullRange))
                    return false;
            }

            if ((op1b == op1) || (op2b == op2) || (op1b == op2b) ||
                ((outRec1 == outRec2) && (Reverse1 == Reverse2)))
                return false;

            if (Reverse1)
            {
                op1b = DupOutPt(op1, false);
                op2b = DupOutPt(op2, true);
                op1->Prev = op2;
                op2->Next = op1;
                op1b->Next = op2b;
                op2b->Prev = op1b;
                j->OutPt1 = op1;
                j->OutPt2 = op1b;
                return true;
            }
            else
            {
                op1b = DupOutPt(op1, true);
                op2b = DupOutPt(op2, false);
                op1->Next = op2;
                op2->Prev = op1;
                op1b->Prev = op2b;
                op2b->Next = op1b;
                j->OutPt1 = op1;
                j->OutPt2 = op1b;
                return true;
            }
        }
    }
    //----------------------------------------------------------------------

    static OutRec *ParseFirstLeft(OutRec *FirstLeft)
    {
        while (FirstLeft && !FirstLeft->Pts)
            FirstLeft = FirstLeft->FirstLeft;
        return FirstLeft;
    }
    //------------------------------------------------------------------------------

    void Clipper::FixupFirstLefts1(OutRec *OldOutRec, OutRec *NewOutRec)
    {
        // tests if NewOutRec contains the polygon before reassigning FirstLeft
        for (PolyOutList::size_type i = 0; i < m_PolyOuts.size(); ++i)
        {
            OutRec *outRec = m_PolyOuts[i];
            OutRec *firstLeft = ParseFirstLeft(outRec->FirstLeft);
            if (outRec->Pts && firstLeft == OldOutRec)
            {
                if (Poly2ContainsPoly1(outRec->Pts, NewOutRec->Pts))
                    outRec->FirstLeft = NewOutRec;
            }
        }
    }
    //----------------------------------------------------------------------

    void Clipper::FixupFirstLefts2(OutRec *InnerOutRec, OutRec *OuterOutRec)
    {
        // A polygon has split into two such that one is now the inner of the other.
        // It's possible that these polygons now wrap around other polygons, so check
        // every polygon that's also contained by OuterOutRec's FirstLeft container
        //(including 0) to see if they've become inner to the new inner polygon ...
        OutRec *orfl = OuterOutRec->FirstLeft;
        for (PolyOutList::size_type i = 0; i < m_PolyOuts.size(); ++i)
        {
            OutRec *outRec = m_PolyOuts[i];

            if (!outRec->Pts || outRec == OuterOutRec || outRec == InnerOutRec)
                continue;
            OutRec *firstLeft = ParseFirstLeft(outRec->FirstLeft);
            if (firstLeft != orfl && firstLeft != InnerOutRec && firstLeft != OuterOutRec)
                continue;
            if (Poly2ContainsPoly1(outRec->Pts, InnerOutRec->Pts))
                outRec->FirstLeft = InnerOutRec;
            else if (Poly2ContainsPoly1(outRec->Pts, OuterOutRec->Pts))
                outRec->FirstLeft = OuterOutRec;
            else if (outRec->FirstLeft == InnerOutRec || outRec->FirstLeft == OuterOutRec)
                outRec->FirstLeft = orfl;
        }
    }
    //----------------------------------------------------------------------
    void Clipper::FixupFirstLefts3(OutRec *OldOutRec, OutRec *NewOutRec)
    {
        // reassigns FirstLeft WITHOUT testing if NewOutRec contains the polygon
        for (PolyOutList::size_type i = 0; i < m_PolyOuts.size(); ++i)
        {
            OutRec *outRec = m_PolyOuts[i];
            OutRec *firstLeft = ParseFirstLeft(outRec->FirstLeft);
            if (outRec->Pts && firstLeft == OldOutRec)
                outRec->FirstLeft = NewOutRec;
        }
    }
    //----------------------------------------------------------------------

    void Clipper::JoinCommonEdges()
    {
        for (JoinList::size_type i = 0; i < m_Joins.size(); i++)
        {
            Join *join = m_Joins[i];

            OutRec *outRec1 = GetOutRec(join->OutPt1->Idx);
            OutRec *outRec2 = GetOutRec(join->OutPt2->Idx);

            if (!outRec1->Pts || !outRec2->Pts)
                continue;
            if (outRec1->IsOpen || outRec2->IsOpen)
                continue;

            // get the polygon fragment with the correct hole state (FirstLeft)
            // before calling JoinPoints() ...
            OutRec *holeStateRec;
            if (outRec1 == outRec2)
                holeStateRec = outRec1;
            else if (OutRec1RightOfOutRec2(outRec1, outRec2))
                holeStateRec = outRec2;
            else if (OutRec1RightOfOutRec2(outRec2, outRec1))
                holeStateRec = outRec1;
            else
                holeStateRec = GetLowermostRec(outRec1, outRec2);

            if (!JoinPoints(join, outRec1, outRec2))
                continue;

            if (outRec1 == outRec2)
            {
                // instead of joining two polygons, we've just created a new one by
                // splitting one polygon into two.
                outRec1->Pts = join->OutPt1;
                outRec1->BottomPt = 0;
                outRec2 = CreateOutRec();
                outRec2->Pts = join->OutPt2;

                // update all OutRec2.Pts Idx's ...
                UpdateOutPtIdxs(*outRec2);

                if (Poly2ContainsPoly1(outRec2->Pts, outRec1->Pts))
                {
                    // outRec1 contains outRec2 ...
                    outRec2->IsHole = !outRec1->IsHole;
                    outRec2->FirstLeft = outRec1;

                    if (m_UsingPolyTree)
                        FixupFirstLefts2(outRec2, outRec1);

                    if ((outRec2->IsHole ^ m_ReverseOutput) == (Area(*outRec2) > 0))
                        ReversePolyPtLinks(outRec2->Pts);
                }
                else if (Poly2ContainsPoly1(outRec1->Pts, outRec2->Pts))
                {
                    // outRec2 contains outRec1 ...
                    outRec2->IsHole = outRec1->IsHole;
                    outRec1->IsHole = !outRec2->IsHole;
                    outRec2->FirstLeft = outRec1->FirstLeft;
                    outRec1->FirstLeft = outRec2;

                    if (m_UsingPolyTree)
                        FixupFirstLefts2(outRec1, outRec2);

                    if ((outRec1->IsHole ^ m_ReverseOutput) == (Area(*outRec1) > 0))
                        ReversePolyPtLinks(outRec1->Pts);
                }
                else
                {
                    // the 2 polygons are completely separate ...
                    outRec2->IsHole = outRec1->IsHole;
                    outRec2->FirstLeft = outRec1->FirstLeft;

                    // fixup FirstLeft pointers that may need reassigning to OutRec2
                    if (m_UsingPolyTree)
                        FixupFirstLefts1(outRec1, outRec2);
                }
            }
            else
            {
                // joined 2 polygons together ...

                outRec2->Pts = 0;
                outRec2->BottomPt = 0;
                outRec2->Idx = outRec1->Idx;

                outRec1->IsHole = holeStateRec->IsHole;
                if (holeStateRec == outRec2)
                    outRec1->FirstLeft = outRec2->FirstLeft;
                outRec2->FirstLeft = outRec1;

                if (m_UsingPolyTree)
                    FixupFirstLefts3(outRec2, outRec1);
            }
        }
    }

    //------------------------------------------------------------------------------
    // ClipperOffset support functions ...
    //------------------------------------------------------------------------------

    DoublePoint GetUnitNormal(const IntPoint &pt1, const IntPoint &pt2)
    {
        if (pt2.X == pt1.X && pt2.Y == pt1.Y)
            return DoublePoint(0, 0);

        double Dx = (double)(pt2.X - pt1.X);
        double dy = (double)(pt2.Y - pt1.Y);
        double f = 1 * 1.0 / std::sqrt(Dx * Dx + dy * dy);
        Dx *= f;
        dy *= f;
        return DoublePoint(dy, -Dx);
    }

    //------------------------------------------------------------------------------
    // ClipperOffset class
    //------------------------------------------------------------------------------

    ClipperOffset::ClipperOffset(double miterLimit, double arcTolerance)
    {
        this->MiterLimit = miterLimit;
        this->ArcTolerance = arcTolerance;
        m_lowest.X = -1;
    }
    //------------------------------------------------------------------------------

    ClipperOffset::~ClipperOffset()
    {
        Clear();
    }
    //------------------------------------------------------------------------------

    void ClipperOffset::Clear()
    {
        for (int i = 0; i < m_polyNodes.ChildCount(); ++i)
            delete m_polyNodes.Childs[i];
        m_polyNodes.Childs.clear();
        m_lowest.X = -1;
    }
    //------------------------------------------------------------------------------

    void ClipperOffset::AddPath(const Path &path, JoinType joinType, EndType endType)
    {
        int highI = (int)path.size() - 1;
        if (highI < 0)
            return;
        PolyNode *newNode = new PolyNode();
        newNode->m_jointype = joinType;
        newNode->m_endtype = endType;

        // strip duplicate points from path and also get index to the lowest point ...
        if (endType == etClosedLine || endType == etClosedPolygon)
            while (highI > 0 && path[0] == path[highI])
                highI--;
        newNode->Contour.reserve(highI + 1);
        newNode->Contour.push_back(path[0]);
        int j = 0, k = 0;
        for (int i = 1; i <= highI; i++)
            if (newNode->Contour[j] != path[i])
            {
                j++;
                newNode->Contour.push_back(path[i]);
                if (path[i].Y > newNode->Contour[k].Y ||
                    (path[i].Y == newNode->Contour[k].Y &&
                     path[i].X < newNode->Contour[k].X))
                    k = j;
            }
        if (endType == etClosedPolygon && j < 2)
        {
            delete newNode;
            return;
        }
        m_polyNodes.AddChild(*newNode);

        // if this path's lowest pt is lower than all the others then update m_lowest
        if (endType != etClosedPolygon)
            return;
        if (m_lowest.X < 0)
            m_lowest = IntPoint(m_polyNodes.ChildCount() - 1, k);
        else
        {
            IntPoint ip = m_polyNodes.Childs[(int)m_lowest.X]->Contour[(int)m_lowest.Y];
            if (newNode->Contour[k].Y > ip.Y ||
                (newNode->Contour[k].Y == ip.Y &&
                 newNode->Contour[k].X < ip.X))
                m_lowest = IntPoint(m_polyNodes.ChildCount() - 1, k);
        }
    }
    //------------------------------------------------------------------------------

    void ClipperOffset::AddPaths(const Paths &paths, JoinType joinType, EndType endType)
    {
        for (Paths::size_type i = 0; i < paths.size(); ++i)
            AddPath(paths[i], joinType, endType);
    }
    //------------------------------------------------------------------------------

    void ClipperOffset::FixOrientations()
    {
        // fixup orientations of all closed paths if the orientation of the
        // closed path with the lowermost vertex is wrong ...
        if (m_lowest.X >= 0 &&
            !Orientation(m_polyNodes.Childs[(int)m_lowest.X]->Contour))
        {
            for (int i = 0; i < m_polyNodes.ChildCount(); ++i)
            {
                PolyNode &node = *m_polyNodes.Childs[i];
                if (node.m_endtype == etClosedPolygon ||
                    (node.m_endtype == etClosedLine && Orientation(node.Contour)))
                    ReversePath(node.Contour);
            }
        }
        else
        {
            for (int i = 0; i < m_polyNodes.ChildCount(); ++i)
            {
                PolyNode &node = *m_polyNodes.Childs[i];
                if (node.m_endtype == etClosedLine && !Orientation(node.Contour))
                    ReversePath(node.Contour);
            }
        }
    }
    //------------------------------------------------------------------------------

    void ClipperOffset::Execute(Paths &solution, double delta)
    {
        solution.clear();
        FixOrientations();
        DoOffset(delta);

        // now clean up 'corners' ...
        Clipper clpr;
        clpr.AddPaths(m_destPolys, ptSubject, true);
        if (delta > 0)
        {
            clpr.Execute(ctUnion, solution, pftPositive, pftPositive);
        }
        else
        {
            IntRect r = clpr.GetBounds();
            Path outer(4);
            outer[0] = IntPoint(r.left - 10, r.bottom + 10);
            outer[1] = IntPoint(r.right + 10, r.bottom + 10);
            outer[2] = IntPoint(r.right + 10, r.top - 10);
            outer[3] = IntPoint(r.left - 10, r.top - 10);

            clpr.AddPath(outer, ptSubject, true);
            clpr.ReverseSolution(true);
            clpr.Execute(ctUnion, solution, pftNegative, pftNegative);
            if (solution.size() > 0)
                solution.erase(solution.begin());
        }
    }
    //------------------------------------------------------------------------------

    void ClipperOffset::Execute(PolyTree &solution, double delta)
    {
        solution.Clear();
        FixOrientations();
        DoOffset(delta);

        // now clean up 'corners' ...
        Clipper clpr;
        clpr.AddPaths(m_destPolys, ptSubject, true);
        if (delta > 0)
        {
            clpr.Execute(ctUnion, solution, pftPositive, pftPositive);
        }
        else
        {
            IntRect r = clpr.GetBounds();
            Path outer(4);
            outer[0] = IntPoint(r.left - 10, r.bottom + 10);
            outer[1] = IntPoint(r.right + 10, r.bottom + 10);
            outer[2] = IntPoint(r.right + 10, r.top - 10);
            outer[3] = IntPoint(r.left - 10, r.top - 10);

            clpr.AddPath(outer, ptSubject, true);
            clpr.ReverseSolution(true);
            clpr.Execute(ctUnion, solution, pftNegative, pftNegative);
            // remove the outer PolyNode rectangle ...
            if (solution.ChildCount() == 1 && solution.Childs[0]->ChildCount() > 0)
            {
                PolyNode *outerNode = solution.Childs[0];
                solution.Childs.reserve(outerNode->ChildCount());
                solution.Childs[0] = outerNode->Childs[0];
                solution.Childs[0]->Parent = outerNode->Parent;
                for (int i = 1; i < outerNode->ChildCount(); ++i)
                    solution.AddChild(*outerNode->Childs[i]);
            }
            else
                solution.Clear();
        }
    }
    //------------------------------------------------------------------------------

    void ClipperOffset::DoOffset(double delta)
    {
        m_destPolys.clear();
        m_delta = delta;

        // if Zero offset, just copy any CLOSED polygons to m_p and return ...
        if (NEAR_ZERO(delta))
        {
            m_destPolys.reserve(m_polyNodes.ChildCount());
            for (int i = 0; i < m_polyNodes.ChildCount(); i++)
            {
                PolyNode &node = *m_polyNodes.Childs[i];
                if (node.m_endtype == etClosedPolygon)
                    m_destPolys.push_back(node.Contour);
            }
            return;
        }

        // see offset_triginometry3.svg in the documentation folder ...
        if (MiterLimit > 2)
            m_miterLim = 2 / (MiterLimit * MiterLimit);
        else
            m_miterLim = 0.5;

        double y;
        if (ArcTolerance <= 0.0)
            y = def_arc_tolerance;
        else if (ArcTolerance > std::fabs(delta) * def_arc_tolerance)
            y = std::fabs(delta) * def_arc_tolerance;
        else
            y = ArcTolerance;
        // see offset_triginometry2.svg in the documentation folder ...
        double steps = pi / std::acos(1 - y / std::fabs(delta));
        if (steps > std::fabs(delta) * pi)
            steps = std::fabs(delta) * pi; // ie excessive precision check
        m_sin = std::sin(two_pi / steps);
        m_cos = std::cos(two_pi / steps);
        m_StepsPerRad = steps / two_pi;
        if (delta < 0.0)
            m_sin = -m_sin;

        m_destPolys.reserve(m_polyNodes.ChildCount() * 2);
        for (int i = 0; i < m_polyNodes.ChildCount(); i++)
        {
            PolyNode &node = *m_polyNodes.Childs[i];
            m_srcPoly = node.Contour;

            int len = (int)m_srcPoly.size();
            if (len == 0 || (delta <= 0 && (len < 3 || node.m_endtype != etClosedPolygon)))
                continue;

            m_destPoly.clear();
            if (len == 1)
            {
                if (node.m_jointype == jtRound)
                {
                    double X = 1.0, Y = 0.0;
                    for (cInt j = 1; j <= steps; j++)
                    {
                        m_destPoly.push_back(IntPoint(
                            Round(m_srcPoly[0].X + X * delta),
                            Round(m_srcPoly[0].Y + Y * delta)));
                        double X2 = X;
                        X = X * m_cos - m_sin * Y;
                        Y = X2 * m_sin + Y * m_cos;
                    }
                }
                else
                {
                    double X = -1.0, Y = -1.0;
                    for (int j = 0; j < 4; ++j)
                    {
                        m_destPoly.push_back(IntPoint(
                            Round(m_srcPoly[0].X + X * delta),
                            Round(m_srcPoly[0].Y + Y * delta)));
                        if (X < 0)
                            X = 1;
                        else if (Y < 0)
                            Y = 1;
                        else
                            X = -1;
                    }
                }
                m_destPolys.push_back(m_destPoly);
                continue;
            }
            // build m_normals ...
            m_normals.clear();
            m_normals.reserve(len);
            for (int j = 0; j < len - 1; ++j)
                m_normals.push_back(GetUnitNormal(m_srcPoly[j], m_srcPoly[j + 1]));
            if (node.m_endtype == etClosedLine || node.m_endtype == etClosedPolygon)
                m_normals.push_back(GetUnitNormal(m_srcPoly[len - 1], m_srcPoly[0]));
            else
                m_normals.push_back(DoublePoint(m_normals[len - 2]));

            if (node.m_endtype == etClosedPolygon)
            {
                int k = len - 1;
                for (int j = 0; j < len; ++j)
                    OffsetPoint(j, k, node.m_jointype);
                m_destPolys.push_back(m_destPoly);
            }
            else if (node.m_endtype == etClosedLine)
            {
                int k = len - 1;
                for (int j = 0; j < len; ++j)
                    OffsetPoint(j, k, node.m_jointype);
                m_destPolys.push_back(m_destPoly);
                m_destPoly.clear();
                // re-build m_normals ...
                DoublePoint n = m_normals[len - 1];
                for (int j = len - 1; j > 0; j--)
                    m_normals[j] = DoublePoint(-m_normals[j - 1].X, -m_normals[j - 1].Y);
                m_normals[0] = DoublePoint(-n.X, -n.Y);
                k = 0;
                for (int j = len - 1; j >= 0; j--)
                    OffsetPoint(j, k, node.m_jointype);
                m_destPolys.push_back(m_destPoly);
            }
            else
            {
                int k = 0;
                for (int j = 1; j < len - 1; ++j)
                    OffsetPoint(j, k, node.m_jointype);

                IntPoint pt1;
                if (node.m_endtype == etOpenButt)
                {
                    int j = len - 1;
                    pt1 = IntPoint((cInt)Round(m_srcPoly[j].X + m_normals[j].X *
                                                                    delta),
                                   (cInt)Round(m_srcPoly[j].Y + m_normals[j].Y * delta));
                    m_destPoly.push_back(pt1);
                    pt1 = IntPoint((cInt)Round(m_srcPoly[j].X - m_normals[j].X *
                                                                    delta),
                                   (cInt)Round(m_srcPoly[j].Y - m_normals[j].Y * delta));
                    m_destPoly.push_back(pt1);
                }
                else
                {
                    int j = len - 1;
                    k = len - 2;
                    m_sinA = 0;
                    m_normals[j] = DoublePoint(-m_normals[j].X, -m_normals[j].Y);
                    if (node.m_endtype == etOpenSquare)
                        DoSquare(j, k);
                    else
                        DoRound(j, k);
                }

                // re-build m_normals ...
                for (int j = len - 1; j > 0; j--)
                    m_normals[j] = DoublePoint(-m_normals[j - 1].X, -m_normals[j - 1].Y);
                m_normals[0] = DoublePoint(-m_normals[1].X, -m_normals[1].Y);

                k = len - 1;
                for (int j = k - 1; j > 0; --j)
                    OffsetPoint(j, k, node.m_jointype);

                if (node.m_endtype == etOpenButt)
                {
                    pt1 = IntPoint((cInt)Round(m_srcPoly[0].X - m_normals[0].X * delta),
                                   (cInt)Round(m_srcPoly[0].Y - m_normals[0].Y * delta));
                    m_destPoly.push_back(pt1);
                    pt1 = IntPoint((cInt)Round(m_srcPoly[0].X + m_normals[0].X * delta),
                                   (cInt)Round(m_srcPoly[0].Y + m_normals[0].Y * delta));
                    m_destPoly.push_back(pt1);
                }
                else
                {
                    k = 1;
                    m_sinA = 0;
                    if (node.m_endtype == etOpenSquare)
                        DoSquare(0, 1);
                    else
                        DoRound(0, 1);
                }
                m_destPolys.push_back(m_destPoly);
            }
        }
    }
    //------------------------------------------------------------------------------

    void ClipperOffset::OffsetPoint(int j, int &k, JoinType jointype)
    {
        // cross product ...
        m_sinA = (m_normals[k].X * m_normals[j].Y - m_normals[j].X * m_normals[k].Y);
        if (std::fabs(m_sinA * m_delta) < 1.0)
        {
            // dot product ...
            double cosA = (m_normals[k].X * m_normals[j].X + m_normals[j].Y * m_normals[k].Y);
            if (cosA > 0) // angle => 0 degrees
            {
                m_destPoly.push_back(IntPoint(Round(m_srcPoly[j].X + m_normals[k].X * m_delta),
                                              Round(m_srcPoly[j].Y + m_normals[k].Y * m_delta)));
                return;
            }
            // else angle => 180 degrees
        }
        else if (m_sinA > 1.0)
            m_sinA = 1.0;
        else if (m_sinA < -1.0)
            m_sinA = -1.0;

        if (m_sinA * m_delta < 0)
        {
            m_destPoly.push_back(IntPoint(Round(m_srcPoly[j].X + m_normals[k].X * m_delta),
                                          Round(m_srcPoly[j].Y + m_normals[k].Y * m_delta)));
            m_destPoly.push_back(m_srcPoly[j]);
            m_destPoly.push_back(IntPoint(Round(m_srcPoly[j].X + m_normals[j].X * m_delta),
                                          Round(m_srcPoly[j].Y + m_normals[j].Y * m_delta)));
        }
        else
            switch (jointype)
            {
            case jtMiter:
            {
                double r = 1 + (m_normals[j].X * m_normals[k].X +
                                m_normals[j].Y * m_normals[k].Y);
                if (r >= m_miterLim)
                    DoMiter(j, k, r);
                else
                    DoSquare(j, k);
                break;
            }
            case jtSquare:
                DoSquare(j, k);
                break;
            case jtRound:
                DoRound(j, k);
                break;
            }
        k = j;
    }
    //------------------------------------------------------------------------------

    void ClipperOffset::DoSquare(int j, int k)
    {
        double dx = std::tan(std::atan2(m_sinA,
                                        m_normals[k].X * m_normals[j].X + m_normals[k].Y * m_normals[j].Y) /
                             4);
        m_destPoly.push_back(IntPoint(
            Round(m_srcPoly[j].X + m_delta * (m_normals[k].X - m_normals[k].Y * dx)),
            Round(m_srcPoly[j].Y + m_delta * (m_normals[k].Y + m_normals[k].X * dx))));
        m_destPoly.push_back(IntPoint(
            Round(m_srcPoly[j].X + m_delta * (m_normals[j].X + m_normals[j].Y * dx)),
            Round(m_srcPoly[j].Y + m_delta * (m_normals[j].Y - m_normals[j].X * dx))));
    }
    //------------------------------------------------------------------------------

    void ClipperOffset::DoMiter(int j, int k, double r)
    {
        double q = m_delta / r;
        m_destPoly.push_back(IntPoint(Round(m_srcPoly[j].X + (m_normals[k].X + m_normals[j].X) * q),
                                      Round(m_srcPoly[j].Y + (m_normals[k].Y + m_normals[j].Y) * q)));
    }
    //------------------------------------------------------------------------------

    void ClipperOffset::DoRound(int j, int k)
    {
        double a = std::atan2(m_sinA,
                              m_normals[k].X * m_normals[j].X + m_normals[k].Y * m_normals[j].Y);
        int steps = std::max((int)Round(m_StepsPerRad * std::fabs(a)), 1);

        double X = m_normals[k].X, Y = m_normals[k].Y, X2;
        for (int i = 0; i < steps; ++i)
        {
            m_destPoly.push_back(IntPoint(
                Round(m_srcPoly[j].X + X * m_delta),
                Round(m_srcPoly[j].Y + Y * m_delta)));
            X2 = X;
            X = X * m_cos - m_sin * Y;
            Y = X2 * m_sin + Y * m_cos;
        }
        m_destPoly.push_back(IntPoint(
            Round(m_srcPoly[j].X + m_normals[j].X * m_delta),
            Round(m_srcPoly[j].Y + m_normals[j].Y * m_delta)));
    }

    //------------------------------------------------------------------------------
    // Miscellaneous public functions
    //------------------------------------------------------------------------------

    void Clipper::DoSimplePolygons()
    {
        PolyOutList::size_type i = 0;
        while (i < m_PolyOuts.size())
        {
            OutRec *outrec = m_PolyOuts[i++];
            OutPt *op = outrec->Pts;
            if (!op || outrec->IsOpen)
                continue;
            do // for each Pt in Polygon until duplicate found do ...
            {
                OutPt *op2 = op->Next;
                while (op2 != outrec->Pts)
                {
                    if ((op->Pt == op2->Pt) && op2->Next != op && op2->Prev != op)
                    {
                        // split the polygon into two ...
                        OutPt *op3 = op->Prev;
                        OutPt *op4 = op2->Prev;
                        op->Prev = op4;
                        op4->Next = op;
                        op2->Prev = op3;
                        op3->Next = op2;

                        outrec->Pts = op;
                        OutRec *outrec2 = CreateOutRec();
                        outrec2->Pts = op2;
                        UpdateOutPtIdxs(*outrec2);
                        if (Poly2ContainsPoly1(outrec2->Pts, outrec->Pts))
                        {
                            // OutRec2 is contained by OutRec1 ...
                            outrec2->IsHole = !outrec->IsHole;
                            outrec2->FirstLeft = outrec;
                            if (m_UsingPolyTree)
                                FixupFirstLefts2(outrec2, outrec);
                        }
                        else if (Poly2ContainsPoly1(outrec->Pts, outrec2->Pts))
                        {
                            // OutRec1 is contained by OutRec2 ...
                            outrec2->IsHole = outrec->IsHole;
                            outrec->IsHole = !outrec2->IsHole;
                            outrec2->FirstLeft = outrec->FirstLeft;
                            outrec->FirstLeft = outrec2;
                            if (m_UsingPolyTree)
                                FixupFirstLefts2(outrec, outrec2);
                        }
                        else
                        {
                            // the 2 polygons are separate ...
                            outrec2->IsHole = outrec->IsHole;
                            outrec2->FirstLeft = outrec->FirstLeft;
                            if (m_UsingPolyTree)
                                FixupFirstLefts1(outrec, outrec2);
                        }
                        op2 = op; // ie get ready for the Next iteration
                    }
                    op2 = op2->Next;
                }
                op = op->Next;
            } while (op != outrec->Pts);
        }
    }
    //------------------------------------------------------------------------------

    void ReversePath(Path &p)
    {
        std::reverse(p.begin(), p.end());
    }
    //------------------------------------------------------------------------------

    void ReversePaths(Paths &p)
    {
        for (Paths::size_type i = 0; i < p.size(); ++i)
            ReversePath(p[i]);
    }
    //------------------------------------------------------------------------------

    void SimplifyPolygon(const Path &in_poly, Paths &out_polys, PolyFillType fillType)
    {
        Clipper c;
        c.StrictlySimple(true);
        c.AddPath(in_poly, ptSubject, true);
        c.Execute(ctUnion, out_polys, fillType, fillType);
    }
    //------------------------------------------------------------------------------

    void SimplifyPolygons(const Paths &in_polys, Paths &out_polys, PolyFillType fillType)
    {
        Clipper c;
        c.StrictlySimple(true);
        c.AddPaths(in_polys, ptSubject, true);
        c.Execute(ctUnion, out_polys, fillType, fillType);
    }
    //------------------------------------------------------------------------------

    void SimplifyPolygons(Paths &polys, PolyFillType fillType)
    {
        SimplifyPolygons(polys, polys, fillType);
    }
    //------------------------------------------------------------------------------

    inline double DistanceSqrd(const IntPoint &pt1, const IntPoint &pt2)
    {
        double Dx = ((double)pt1.X - pt2.X);
        double dy = ((double)pt1.Y - pt2.Y);
        return (Dx * Dx + dy * dy);
    }
    //------------------------------------------------------------------------------

    double DistanceFromLineSqrd(
        const IntPoint &pt, const IntPoint &ln1, const IntPoint &ln2)
    {
        // The equation of a line in general form (Ax + By + C = 0)
        // given 2 points (x?y? & (x?y? is ...
        //(y?- y?x + (x?- x?y + (y?- y?x?- (x?- x?y?= 0
        // A = (y?- y?; B = (x?- x?; C = (y?- y?x?- (x?- x?y?
        // perpendicular distance of point (x?y? = (Ax?+ By?+ C)/Sqrt(A?+ B?
        // see http://en.wikipedia.org/wiki/Perpendicular_distance
        double A = double(ln1.Y - ln2.Y);
        double B = double(ln2.X - ln1.X);
        double C = A * ln1.X + B * ln1.Y;
        C = A * pt.X + B * pt.Y - C;
        return (C * C) / (A * A + B * B);
    }
    //---------------------------------------------------------------------------

    bool SlopesNearCollinear(const IntPoint &pt1,
                             const IntPoint &pt2, const IntPoint &pt3, double distSqrd)
    {
        // this function is more accurate when the point that's geometrically
        // between the other 2 points is the one that's tested for distance.
        // ie makes it more likely to pick up 'spikes' ...
        if (Abs(pt1.X - pt2.X) > Abs(pt1.Y - pt2.Y))
        {
            if ((pt1.X > pt2.X) == (pt1.X < pt3.X))
                return DistanceFromLineSqrd(pt1, pt2, pt3) < distSqrd;
            else if ((pt2.X > pt1.X) == (pt2.X < pt3.X))
                return DistanceFromLineSqrd(pt2, pt1, pt3) < distSqrd;
            else
                return DistanceFromLineSqrd(pt3, pt1, pt2) < distSqrd;
        }
        else
        {
            if ((pt1.Y > pt2.Y) == (pt1.Y < pt3.Y))
                return DistanceFromLineSqrd(pt1, pt2, pt3) < distSqrd;
            else if ((pt2.Y > pt1.Y) == (pt2.Y < pt3.Y))
                return DistanceFromLineSqrd(pt2, pt1, pt3) < distSqrd;
            else
                return DistanceFromLineSqrd(pt3, pt1, pt2) < distSqrd;
        }
    }
    //------------------------------------------------------------------------------

    bool PointsAreClose(IntPoint pt1, IntPoint pt2, double distSqrd)
    {
        double Dx = (double)pt1.X - pt2.X;
        double dy = (double)pt1.Y - pt2.Y;
        return ((Dx * Dx) + (dy * dy) <= distSqrd);
    }
    //------------------------------------------------------------------------------

    OutPt *ExcludeOp(OutPt *op)
    {
        OutPt *result = op->Prev;
        result->Next = op->Next;
        op->Next->Prev = result;
        result->Idx = 0;
        return result;
    }
    //------------------------------------------------------------------------------

    void CleanPolygon(const Path &in_poly, Path &out_poly, double distance)
    {
        // distance = proximity in units/pixels below which vertices
        // will be stripped. Default ~= sqrt(2).

        size_t size = in_poly.size();

        if (size == 0)
        {
            out_poly.clear();
            return;
        }

        OutPt *outPts = new OutPt[size];
        for (size_t i = 0; i < size; ++i)
        {
            outPts[i].Pt = in_poly[i];
            outPts[i].Next = &outPts[(i + 1) % size];
            outPts[i].Next->Prev = &outPts[i];
            outPts[i].Idx = 0;
        }

        double distSqrd = distance * distance;
        OutPt *op = &outPts[0];
        while (op->Idx == 0 && op->Next != op->Prev)
        {
            if (PointsAreClose(op->Pt, op->Prev->Pt, distSqrd))
            {
                op = ExcludeOp(op);
                size--;
            }
            else if (PointsAreClose(op->Prev->Pt, op->Next->Pt, distSqrd))
            {
                ExcludeOp(op->Next);
                op = ExcludeOp(op);
                size -= 2;
            }
            else if (SlopesNearCollinear(op->Prev->Pt, op->Pt, op->Next->Pt, distSqrd))
            {
                op = ExcludeOp(op);
                size--;
            }
            else
            {
                op->Idx = 1;
                op = op->Next;
            }
        }

        if (size < 3)
            size = 0;
        out_poly.resize(size);
        for (size_t i = 0; i < size; ++i)
        {
            out_poly[i] = op->Pt;
            op = op->Next;
        }
        delete[] outPts;
    }
    //------------------------------------------------------------------------------

    void CleanPolygon(Path &poly, double distance)
    {
        CleanPolygon(poly, poly, distance);
    }
    //------------------------------------------------------------------------------

    void CleanPolygons(const Paths &in_polys, Paths &out_polys, double distance)
    {
        out_polys.resize(in_polys.size());
        for (Paths::size_type i = 0; i < in_polys.size(); ++i)
            CleanPolygon(in_polys[i], out_polys[i], distance);
    }
    //------------------------------------------------------------------------------

    void CleanPolygons(Paths &polys, double distance)
    {
        CleanPolygons(polys, polys, distance);
    }
    //------------------------------------------------------------------------------

    void Minkowski(const Path &poly, const Path &path,
                   Paths &solution, bool isSum, bool isClosed)
    {
        int delta = (isClosed ? 1 : 0);
        size_t polyCnt = poly.size();
        size_t pathCnt = path.size();
        Paths pp;
        pp.reserve(pathCnt);
        if (isSum)
            for (size_t i = 0; i < pathCnt; ++i)
            {
                Path p;
                p.reserve(polyCnt);
                for (size_t j = 0; j < poly.size(); ++j)
                    p.push_back(IntPoint(path[i].X + poly[j].X, path[i].Y + poly[j].Y));
                pp.push_back(p);
            }
        else
            for (size_t i = 0; i < pathCnt; ++i)
            {
                Path p;
                p.reserve(polyCnt);
                for (size_t j = 0; j < poly.size(); ++j)
                    p.push_back(IntPoint(path[i].X - poly[j].X, path[i].Y - poly[j].Y));
                pp.push_back(p);
            }

        solution.clear();
        solution.reserve((pathCnt + delta) * (polyCnt + 1));
        for (size_t i = 0; i < pathCnt - 1 + delta; ++i)
            for (size_t j = 0; j < polyCnt; ++j)
            {
                Path quad;
                quad.reserve(4);
                quad.push_back(pp[i % pathCnt][j % polyCnt]);
                quad.push_back(pp[(i + 1) % pathCnt][j % polyCnt]);
                quad.push_back(pp[(i + 1) % pathCnt][(j + 1) % polyCnt]);
                quad.push_back(pp[i % pathCnt][(j + 1) % polyCnt]);
                if (!Orientation(quad))
                    ReversePath(quad);
                solution.push_back(quad);
            }
    }
    //------------------------------------------------------------------------------

    void MinkowskiSum(const Path &pattern, const Path &path, Paths &solution, bool pathIsClosed)
    {
        Minkowski(pattern, path, solution, true, pathIsClosed);
        Clipper c;
        c.AddPaths(solution, ptSubject, true);
        c.Execute(ctUnion, solution, pftNonZero, pftNonZero);
    }
    //------------------------------------------------------------------------------

    void TranslatePath(const Path &input, Path &output, const IntPoint delta)
    {
        // precondition: input != output
        output.resize(input.size());
        for (size_t i = 0; i < input.size(); ++i)
            output[i] = IntPoint(input[i].X + delta.X, input[i].Y + delta.Y);
    }
    //------------------------------------------------------------------------------

    void MinkowskiSum(const Path &pattern, const Paths &paths, Paths &solution, bool pathIsClosed)
    {
        Clipper c;
        for (size_t i = 0; i < paths.size(); ++i)
        {
            Paths tmp;
            Minkowski(pattern, paths[i], tmp, true, pathIsClosed);
            c.AddPaths(tmp, ptSubject, true);
            if (pathIsClosed)
            {
                Path tmp2;
                TranslatePath(paths[i], tmp2, pattern[0]);
                c.AddPath(tmp2, ptClip, true);
            }
        }
        c.Execute(ctUnion, solution, pftNonZero, pftNonZero);
    }
    //------------------------------------------------------------------------------

    void MinkowskiDiff(const Path &poly1, const Path &poly2, Paths &solution)
    {
        Minkowski(poly1, poly2, solution, false, true);
        Clipper c;
        c.AddPaths(solution, ptSubject, true);
        c.Execute(ctUnion, solution, pftNonZero, pftNonZero);
    }
    //------------------------------------------------------------------------------

    enum NodeType
    {
        ntAny,
        ntOpen,
        ntClosed
    };

    void AddPolyNodeToPaths(const PolyNode &polynode, NodeType nodetype, Paths &paths)
    {
        bool match = true;
        if (nodetype == ntClosed)
            match = !polynode.IsOpen();
        else if (nodetype == ntOpen)
            return;

        if (!polynode.Contour.empty() && match)
            paths.push_back(polynode.Contour);
        for (int i = 0; i < polynode.ChildCount(); ++i)
            AddPolyNodeToPaths(*polynode.Childs[i], nodetype, paths);
    }
    //------------------------------------------------------------------------------

    void PolyTreeToPaths(const PolyTree &polytree, Paths &paths)
    {
        paths.resize(0);
        paths.reserve(polytree.Total());
        AddPolyNodeToPaths(polytree, ntAny, paths);
    }
    //------------------------------------------------------------------------------

    void ClosedPathsFromPolyTree(const PolyTree &polytree, Paths &paths)
    {
        paths.resize(0);
        paths.reserve(polytree.Total());
        AddPolyNodeToPaths(polytree, ntClosed, paths);
    }
    //------------------------------------------------------------------------------

    void OpenPathsFromPolyTree(PolyTree &polytree, Paths &paths)
    {
        paths.resize(0);
        paths.reserve(polytree.Total());
        // Open paths are top level only, so ...
        for (int i = 0; i < polytree.ChildCount(); ++i)
            if (polytree.Childs[i]->IsOpen())
                paths.push_back(polytree.Childs[i]->Contour);
    }
    //------------------------------------------------------------------------------

    std::ostream &operator<<(std::ostream &s, const IntPoint &p)
    {
        s << "(" << p.X << "," << p.Y << ")";
        return s;
    }
    //------------------------------------------------------------------------------

    std::ostream &operator<<(std::ostream &s, const Path &p)
    {
        if (p.empty())
            return s;
        Path::size_type last = p.size() - 1;
        for (Path::size_type i = 0; i < last; i++)
            s << "(" << p[i].X << "," << p[i].Y << "), ";
        s << "(" << p[last].X << "," << p[last].Y << ")\n";
        return s;
    }
    //------------------------------------------------------------------------------

    std::ostream &operator<<(std::ostream &s, const Paths &p)
    {
        for (Paths::size_type i = 0; i < p.size(); i++)
            s << p[i];
        s << "\n";
        return s;
    }
    //------------------------------------------------------------------------------

} // ClipperLib namespace
#endif